Pivotal bone anchor assembly with insert tool deployment

ABSTRACT

A pivotal bone anchor assembly includes a receiver with an open channel configured to receive an elongate rod and a central bore having an inwardly protruding interference structure with a discontinuous annular upper surface. The assembly also includes a shank having a head positionable within the central bore and an anchor portion for fixation to the bone of a patient, and an insert positionable into the central bore in an initial position that is constrained from vertical movement in at least one direction by engagement between outer curvate side surfaces of the insert and the discontinuous annular upper surface. The insert is configured for forced downward displacement within the central bore by tooling from the initial position to a lower position in which the outer curvate side surfaces of the insert are wedged against the interference structure to inhibit the insert from moving back up within the central bore.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/675,431 filed Nov. 6, 2019, which is a continuation of U.S.application Ser. No. 16/247,378 filed Jan. 14, 2019, now U.S. Pat. No.10,478,225, which is a continuation of U.S. application Ser. No.15/893,333 filed Feb. 9, 2018, now U.S. Pat. No. 10,179,010, which is acontinuation of U.S. application Ser. No. 13/373,289, filed Nov. 9,2011, now U.S. Pat. No. 9,907,574, which claims the benefit of U.S.Provisional Patent Application No. 61/460,234, filed Dec. 29, 2010, andU.S. Provisional Patent Application No. 61/456,649, filed Nov. 10, 2010,each of which is incorporated by reference in its entirety herein.

U.S. application Ser. No. 13/373,289 is also a continuation-in-part ofU.S. application Ser. No. 12/924,802, filed Oct. 5, 2010, now U.S. Pat.No. 8,556,938, which claims the benefit of the following U.S.Provisional Patent Application Nos.: 61/278,240, filed Oct. 5, 2009;61/336,911, filed Jan. 28, 2010; 61/343,737, filed May 3, 2010;61/395,564, filed May 14, 2010; 61/395,752, filed May 17, 2010;61/396,390, filed May 26, 2010; 61/398,807, filed Jul. 1, 2010;61/400,504, filed Jul. 29, 2010; 61/402,959, filed Sep. 8, 2010;61/403,696, filed Sep. 20, 2010; and 61/403,915, filed Sep. 23, 2010,each of which is incorporated by reference in its entirety herein.

U.S. application Ser. No. 13/373,289 is also a continuation-in-part ofU.S. application Ser. No. 12/802,849 filed Jun. 15, 2010, now abandoned,which claims the benefit of the following U.S. Provisional PatentApplication Nos.: 61/268,708, filed Jun. 15, 2009; 61/270,754, filedJul. 13, 2009; 61/336,911, filed Jan. 28, 2010; 61/395,564, filed May14, 2010; 61/395,752, filed May 17, 2010; and 61/396,390, filed May 26,2010, each of which is incorporated by reference in its entirety herein.

BACKGROUND OF THE INVENTION

The present invention is directed to polyaxial bone screw shanks withheads for use in bone surgery, more specifically to spinal surgery andparticularly to such screws with receiver member assemblies includingcompression or pressure inserts and expansion-only split retainers tosnap over, capture and retain the bone screw shank head in the receivermember assembly and later fix the bone screw shank with respect to thereceiver assembly.

Bone screws are utilized in many types of spinal surgery in order tosecure various implants to vertebrae along the spinal column for thepurpose of stabilizing and/or adjusting spinal alignment. Although bothclosed-ended and open-ended bone screws are known, open-ended screws areparticularly well suited for connections to rods and connector arms,because such rods or arms do not need to be passed through a closedbore, but rather can be laid or urged into an open channel within areceiver or head of such a screw. Generally, the screws must be insertedinto the bone as an integral unit along with the head, or as apreassembled unit in the form of a shank and pivotal receiver, such as apolyaxial bone screw assembly.

Typical open-ended bone screws include a threaded shank with a pair ofparallel projecting branches or arms which form a yoke with a U-shapedslot or channel to receive a rod. Hooks and other types of connectors,as are used in spinal fixation techniques, may also include similar openends for receiving rods or portions of other fixation and stabilizationstructure.

A common approach for providing vertebral column support is to implantbone screws into certain bones which then in turn support a longitudinalstructure such as a rod, or are supported by such a rod. Bone screws ofthis type may have a fixed head or receiver relative to a shank thereof,or may be of a polyaxial screw nature. In the fixed bone screws, the rodreceiver head cannot be moved relative to the shank and the rod must befavorably positioned in order for it to be placed within the receiverhead. This is sometimes very difficult or impossible to do. Therefore,polyaxial bone screws are commonly preferred. Open-ended polyaxial bonescrews typically allow for a loose or floppy rotation of the head orreceiver about the shank until a desired rotational position of thereceiver is achieved by fixing such position relative to the shankduring a final stage of a medical procedure when a rod or otherlongitudinal connecting member is inserted into the receiver, followedby a locking screw or other closure. This floppy feature can be, in somecases, undesirable and make the procedure more difficult. Also, it isoften desirable to insert the bone screw shank separate from thereceiver or head due to its bulk which can get in the way of what thesurgeon needs to do. Such screws that allow for this capability aresometimes referred to as modular polyaxial screws.

With specific reference to modular snap-on or pop-on polyaxial pediclescrew systems having shank receiver assemblies, the prior art has shownand taught the concept of the receiver and certain retainer partsforming an assembly wherein a contractile locking engagement between theparts is created to fix the shank head with respect to the receiver andretainer. The receiver and shank head retainer assemblies in the priorart have included a contractile retainer ring and/or a lower pressureinsert with an expansion and contraction collet-type of structure havingcontractile locking engagement for the shank head due to direct contactbetween the retainer and/or the collet structure with the receiverresulting in contraction of the retainer ring and/or the collet-typestructure of the insert against the shank head.

The prior art for modular polyaxial screw assemblies has also shown andtaught that the contact surfaces on the outside of the collect and/orretainer and the inside of the receiver can be tapered, conical,radiused, spherical, curvate, multi-curvate, rounded, as well as otherconfigurations to create a contractile type of locking engagement forthe shank head with respect to the receiver.

In addition, the prior art for modular polyaxial screw assemblies hasshown and taught that the shank head can both enter and escape from acollet-like structure on the insert or from the retainer when the insertor retainer is in the up position and within the expansion recess orchamber of the receiver. This is the case unless the insert and/or theretainer are blocked from being able to be pushed back up into receiverbore or cavity.

SUMMARY OF THE INVENTION

The present invention differentiates from the prior art by not allowingthe receiver to be removed from the shank head once the parts aresnapped-on and connected. This is true even if the retainer can go backup into the expansion chamber. This approach or design has been found tobe more secure and to provide more resistance to pull-out forcescompared to the prior art for modular polyaxial screw designs.Collect-like structures extending downwardly from lower pressureinserts, when used in modular polyaxial screw designs, as shown in theprior art, have been found to be somewhat weak with respect to pull-outforces encountered during some spinal reduction procedures. The presentinvention is designed to solve these problems.

The present invention also differentiates from all of the prior art byproviding a split retainer ring with a collet-like upper structureportion, wherein the collet-like structure does not participate at allin the locking engagement for the shank head with respect to thereceiver. In addition, the retainer ring itself for the presentinvention is uniquely characterized by a base portion providingexpansion to receive and capture the shank head and then having onlyexpansion (not contraction) locking engagement between the shank headand the retainer ring base and between the retainer ring base andhorizontal and vertical loading surfaces near a bottom opening of thereceiver.

The expansion-only retainer ring base in the present invention ispositioned entirely below the shank head hemisphere in the receiver andcan be a stronger, more substantial structure to resist larger pull outforces on the assembly. The retainer ring base can also be bettersupported on a generally horizontal loading surface near the loweropening in the bottom of the receiver. This design has been found to bestronger and more secure when compared to that of the prior art whichuses some type of contractile locking engagement between the parts, asdescribed above; and, again, once assembled it cannot be disassembled.

Thus, a polyaxial bone screw assembly according to the inventionincludes a shank having an integral upper portion or integral sphericalhead and a body for fixation to a bone; a separate receiver defining anupper open channel, a central bore, a lower cavity and a lower opening;an insert that may be top drop and turn in place or may have extendedportions that are received in the receiver channel; and a friction fitresilient expansion-only split retainer for capturing the shank head inthe receiver lower cavity, the shank head being frictionally engagedwith, but still movable in a non-floppy manner with respect to thefriction fit retainer and the receiver prior to locking of the shankinto a desired configuration. The compression insert operatively engagesthe shank head and is spaced from the retainer by the head that issnapped into the resilient retainer. The shank is finally locked into afixed position relative to the receiver by frictional engagement betweenthe insert and a lower split ring-like portion of the retainer, asdescribed previously, due to a downward force placed on the compressioninsert by a closure top pressing on a rod, or other longitudinalconnecting member, captured within the receiver bore and channel. In theillustrated embodiments, retainers and compression inserts aredownloaded into the receiver, but uploaded embodiments are alsoforeseen. The shank head can be positioned into the receiver lowercavity at the lower opening thereof prior to or after insertion of theshank into bone. Some compression inserts include a lock and releasefeature for independent locking of the polyaxial mechanism so the screwcan be used like a fixed monoaxial screw. The shank can be cannulatedfor minimally invasive surgery applications. The receiver can have crimptabs, but is devoid of any type of spring tabs or collet-likestructures. The lower pressure insert and/or the retainer are bothdevoid of any type of receiver-retainer contractile locking engagementswith respect to the shank head. The retainer can also have upwardlyextending spring tabs which are deployed into openings in the receivercavity so that the retainer and captured shank head are stabilized andfully constrained in the region of the receiver locking chamber oncethey enter into this lower portion of the receiver cavity. In this way,the shank head and retainer cannot go back up into the receiver cavity.

Again, a pre-assembled receiver, compression insert and friction fitsplit retainer may be “pushed-on”, “snapped-on” or “popped-on” to theshank head prior to or after implantation of the shank into a vertebra.Such a “snapping on” procedure includes the steps of uploading the shankhead into the receiver lower opening, the shank head pressing againstthe base portion of the split retainer ring and expanding the resilientlower open retainer portion out into an expansion portion or chamber ofthe receiver cavity followed by an elastic return of the retainer backto an original or nominal shape thereof after the hemisphere of theshank head or upper portion passes through the lower ring-like portionof the retainer. The shank head also enters into the friction fit upperportion of the retainer, the panels of the friction fit portion of theretainer snapping onto the shank head as the retainer returns to aneutral or close to neutral orientation, providing a non-floppyconnection between the retainer and the shank head. The friction fitbetween the shank head and the retainer is temporary and not part of thefinal locking mechanism. In the illustrated embodiments, when the shankis ultimately locked between the compression insert and the lowerportion of the retainer, the friction fit collet-like panels of theretainer are no longer in a friction fit engagement with the shank headand they are not in contact with the receiver. The final fixation occursas a result of a locking expansion-type of contact between the shankhead and the lower portion of the split retainer and an expansion-typeof non-tapered locking engagement between the lower portion of theretainer ring and the locking chamber in the lower portion of thereceiver cavity. The retainer can expand more in the upper portion orexpansion chamber of the receiver cavity to allow the shank head to passthrough, but has restricted expansion to retain the shank head when theretainer lower ring portion is against the locking chamber surfaces inthe lower portion of the receiver cavity and the shank head is forceddown against the retainer ring during final locking. In someembodiments, when the polyaxial mechanism is locked, the insert isforced or wedged against a surface of the receiver resulting in aninterference locking engagement, allowing for adjustment or removal ofthe rod or other connecting member without loss of a desired angularrelationship between the shank and the receiver. This independentlocking feature allows the polyaxial screw to function like a fixedmonoaxial screw.

The lower pressure insert may also be configured to be independentlylocked by a tool or instrument, thereby allowing the pop-on polyaxialscrew to be distracted, compressed and/or rotated along and around therod to provide for improved spinal correction techniques. Such a toolengages the pop-on receiver from the sides and then engages the insertto force the insert down into a locked position within the receiver. Inthe illustrated embodiments, both the receiver and the insert includeapertures having tool receiving surfaces that are disposed at an obliqueangle with respect to a central axis of the receiver. Such slopingsurfaces of the receiver and the insert align and provide a path forsuch a locking tool to be inserted through the receiver at arm surfacesthereof and against the insert in a downwardly directed angle towardsthe head of the shank. With the locking tool still in place and adesired correction maintained, the rod is then locked within thereceiver channel by a closure top followed by removal of the tool. Thisprocess may involve multiple screws all being manipulated simultaneouslywith multiple tools to achieve the desired correction.

It is noted that once the shank head is captured by the retainer ringand the retainer and head are moved down into the locking chamber regionof the receiver cavity, retainer spring tabs are deployed outwardlystabilizing the retainer so that the retainer cannot go back up into thereceiver cavity. This spring tab deployment also creates good rotationalstability between the retainer and receiver and provides for anadditional rotational friction fit between the shank head and thereceiver itself since the retainer cannot axially rotate in thereceiver.

Objects of the invention further include providing apparatus and methodsthat are easy to use and especially adapted for the intended use thereofand wherein the tools are comparatively inexpensive to produce. Otherobjects and advantages of this invention will become apparent from thefollowing description taken in conjunction with the accompanyingdrawings wherein are set forth, by way of illustration and example,certain embodiments of this invention.

The drawings constitute a part of this specification and includeexemplary embodiments of the present invention and illustrate variousobjects and features thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded front elevational view of a polyaxial bone screwassembly according to the present invention including a shank, areceiver, an open friction fit expansion-only retainer and a top dropand turn in place lower compression insert, further shown with a portionof a longitudinal connecting member in the form of a rod and a closuretop.

FIG. 2 is an enlarged top plan view of the shank of FIG. 1.

FIG. 3 is reduced cross-sectional view taken along the line 3-3 of FIG.2.

FIG. 4 is an enlarged side elevational view of the receiver of FIG. 1.

FIG. 5 is an enlarged perspective view of the receiver of FIG. 4.

FIG. 6 is an enlarged top plan view of the receiver of FIG. 4.

FIG. 7 is an enlarged bottom plan view of the receiver of FIG. 4.

FIG. 8 is an enlarged cross-sectional view taken along the line 8-8 ofFIG. 6.

FIG. 9 is an enlarged cross-sectional view taken along the line 9-9 ofFIG. 6.

FIG. 10 is an enlarged perspective view of the retainer of FIG. 1.

FIG. 11 is a reduced side elevational view of the retainer of FIG. 10.

FIG. 12 is a top plan view of the retainer of FIG. 10.

FIG. 13 is a reduced bottom plan view of the retainer of FIG. 10.

FIG. 14 is a reduced cross-sectional view taken along the line 14-14 ofFIG. 12.

FIG. 15 is a reduced cross-sectional view taken along the line 15-15 ofFIG. 12.

FIG. 16 is an enlarged perspective view of the insert of FIG. 1.

FIG. 17 is a side elevational view of the insert of FIG. 16.

FIG. 18 is a top plan view of the insert of FIG. 16.

FIG. 19 is a bottom plan view of the insert of FIG. 16.

FIG. 20 is an enlarged cross-sectional view taken along the line 20-20of FIG. 18.

FIG. 21 is an enlarged cross-sectional view taken along the line 21-21of FIG. 18.

FIG. 22 is an enlarged front elevational view of the retainer andreceiver of FIG. 1 with portions of the receiver broken away to show thedetail thereof, the retainer being shown downloaded into the receiver(in phantom) to a partially inserted stage of assembly.

FIG. 23 is a front elevational view of the retainer and receiver withportions broken away, similar to what is shown in FIG. 22, showing theretainer in a subsequent stage of assembly.

FIG. 24 is a front elevational view of the retainer and receiver withportions broken away, similar to what is shown in FIG. 23, showing theretainer in a subsequent stage of assembly.

FIG. 25 is a front elevational view of the retainer and receiver withportions broken away, similar to what is shown in FIG. 24, showing theretainer in a subsequent stage of assembly.

FIG. 26 is a front elevational view of the retainer and receiver withportions broken away, similar to what is shown in FIG. 25, showing theretainer in a subsequent stage of assembly.

FIG. 27 is a front elevational view of the retainer and receiver withportions broken away, similar to what is shown in FIG. 26, furthershowing an enlarged side elevational view of the insert of FIG. 1 (inphantom) above the receiver and then in solid lines being downloadedinto the receiver to a partially inserted stage of assembly.

FIG. 28 is a front elevational view with portions broken away, similarto FIG. 27, showing the insert rotated into a position in alignment withthe receiver.

FIG. 29 is a perspective view, with portions broken away, of thereceiver, retainer and insert of FIG. 28.

FIG. 30 is an enlarged perspective view of the receiver, retainer andinsert of FIG. 29, further showing the receiver crimped to the insert.

FIG. 31 is a reduced front elevational view of the receiver, retainerand insert of FIG. 30 with portions broken away to show the detailthereof, showing the retainer spring tab arms placed in a desired upwardposition within the receiver so that the retainer spring tabs pushresiliently outwardly against the receiver, holding the retainer againstthe receiver and keeping the insert in an upward position duringshipping.

FIG. 32 is a front elevational view with portions broken away, similarto FIG. 31, and further showing an enlarged and partial shank of FIG. 1in a first stage of assembly with the retainer, a hemisphere of theshank head and a vertebra portion are both shown in phantom.

FIG. 33 is a partial front elevational view with portions broken away,similar to FIG. 32, showing the retainer lower portion in an expandedstate about a mid-portion of the shank head, the head hemisphere shownin phantom.

FIG. 34 is a reduced partial front elevational view with portions brokenaway, similar to FIG. 33, the shank upper portion or head in frictionalengagement with an upper portion of the retainer.

FIG. 35 is a partial front elevational view with portions broken away,similar to FIG. 34, the shank upper portion with attached retainer beingshown pulled down into a seated position within the lower receivercavity, the retainer spring tabs in a substantially neutral state,extending outwardly partially into receiver apertures.

FIG. 36 is an enlarged and partial front elevational view with portionsbroken away of all of the components shown in FIG. 1, the assembly ofFIG. 35 shown in a stage of assembly with the rod and closure top.

FIG. 37 is a partial front elevational view with portions broken away,similar to FIG. 36, shown in a final locking position.

FIG. 38 is an enlarged perspective view of an alternative locking insertfor use with the assembly of FIG. 1 in lieu of the insert shown in FIG.1.

FIG. 39 is a side elevational view of the insert of FIG. 38.

FIG. 40 is a front elevational view of the insert of FIG. 38.

FIG. 41 is a top plan view of the insert of FIG. 38.

FIG. 42 is a bottom plan view of the insert of FIG. 38.

FIG. 43 is a cross-sectional view taken along the line 43-43 of FIG. 41.

FIG. 44 is a cross-sectional view taken along the line 44-44 of FIG. 41.

FIG. 45 is an enlarged and partial front elevational view with portionsbroken away of the receiver and retainer of FIG. 1 and the insert ofFIG. 38, shown in an un-locked shipping position.

FIG. 46 is a reduced side elevational view of the assembly of FIG. 45further showing the receiver crimped to the insert.

FIG. 47 is a reduced and partial front elevational view of the shank,receiver, retainer, rod and closure of FIG. 1 and the insert of FIG. 38,shown with portions broken away and in a final stage of assembly.

FIG. 48 is an enlarged and partial front elevational view with portionsbroken away, similar to FIG. 47, shown fully assembled and in a finallocked position.

FIG. 49 is an enlarged and partial front elevational view with portionsbroken away, similar to FIG. 48, showing the shank, retainer, insert andreceiver remaining in a locked position after removal of the rod andclosure top of FIG. 1 and further showing, in exploded view, analternative deformable rod and cooperating alternative closure top.

FIG. 50 is a reduced and partial front elevational view with portionsbroken away, similar to FIG. 49, showing the alternative rod and closuretop fixed to the remainder of the assembly.

FIG. 51 is a reduced and partial front elevational view with portionsbroken away of the assembly of FIG. 49 without the alternative rod andclosure top, and further showing unlocking of the insert from thereceiver with a two-piece tool having an inner insert engaging portionand an outer tubular holding portion.

FIG. 52 is a reduced and partial front elevational view of the two-piecetool of FIG. 51, holding prongs of the inner insert engaging portionbeing shown in phantom.

FIG. 53 is an enlarged and partial front elevational view of the innerinsert engaging portion of the tool shown in FIG. 52 with portionsbroken away to show the detail thereof.

FIG. 54 is an enlarged and partial perspective view of the assembly ofFIG. 1, shown in a position similar to what is shown in FIG. 47, butwith the shank being at an angle with respect to the receiver andfurther showing an alternative locking tool for independently lockingthe insert into an interference fit with the receiver and thus lockingthe shank with respect to the receiver even when the closure top and rodare in a loose, unlocked relationship with the receiver as shown.

FIG. 55 is a partial perspective view of a portion of the locking toolof FIG. 54.

FIG. 56 is an enlarged and partial front elevational view of theassembly and locking tool of FIG. 54 with portions broken away to shownthe detail thereof.

FIG. 57 is an enlarged perspective view of another alternative andnon-locking insert for use with the assembly of FIG. 1 in lieu of theinsert shown in FIG. 1.

FIG. 58 is a partial front elevational view, similar to FIG. 56, withportions broken away to show the detail thereof, showing the assembly ofFIG. 1 with the alternative insert of FIG. 57 and showing the lockingtool pressing the insert into a locked position with respect to aremainder of the assembly.

FIG. 59 is an exploded front elevational view of another polyaxial bonescrew assembly according to the present invention including a shank, areceiver, an open friction fit expansion-only retainer and a lowercompression insert, further shown with a portion of a longitudinalconnecting member in the form of a rod and a closure top.

FIG. 60 is an enlarged top plan view of the shank of FIG. 59.

FIG. 61 is reduced cross-sectional view taken along the line 61-61 ofFIG. 60.

FIG. 62 is an enlarged side elevational view of the receiver of FIG. 59.

FIG. 63 is an enlarged perspective view of the receiver of FIG. 62.

FIG. 64 is an enlarged top plan view of the receiver of FIG. 62.

FIG. 65 is an enlarged bottom plan view of the receiver of FIG. 62.

FIG. 66 is an enlarged cross-sectional view taken along the line 66-66of FIG. 64.

FIG. 67 is an enlarged cross-sectional view taken along the line 67-67of FIG. 64.

FIG. 68 is an enlarged perspective view of the retainer of FIG. 59.

FIG. 69 is a reduced side elevational view of the retainer of FIG. 68.

FIG. 70 is a top plan view of the retainer of FIG. 68.

FIG. 71 is a reduced bottom plan view of the retainer of FIG. 68.

FIG. 72 is a cross-sectional view taken along the line 72-72 of FIG. 70.

FIG. 73 is a cross-sectional view taken along the line 73-73 of FIG. 70.

FIG. 74 is an enlarged perspective view of the insert of FIG. 59.

FIG. 75 is a front elevational view of the insert of FIG. 74.

FIG. 76 is a top plan view of the insert of FIG. 74.

FIG. 77 is a bottom plan view of the insert of FIG. 74.

FIG. 78 is an enlarged cross-sectional view taken along the line 78-78of FIG. 76.

FIG. 79 is an enlarged cross-sectional view taken along the line 79-79of FIG. 76.

FIG. 80 is an enlarged front elevational view of the retainer andreceiver of FIG. 59 with portions of the receiver broken away to showthe detail thereof, the retainer being shown downloaded into thereceiver (in phantom) to a partially inserted stage of assembly.

FIG. 81 is a front elevational view of the retainer and receiver withportions broken away, similar to what is shown in FIG. 80, showing theretainer in a subsequent stage of assembly.

FIG. 82 is a front elevational view of the retainer and receiver withportions broken away, similar to what is shown in FIG. 81, also showingthe insert being downloaded into the receiver (in phantom) to apartially inserted stage of assembly.

FIG. 83 is a front elevational view of the retainer, receiver and insertwith portions broken away, similar to what is shown in FIG. 82, showingthe retainer and insert in a subsequent stage of assembly, the retainerspring tabs being pressed inwardly and the insert being captured by thereceiver.

FIG. 84 is an enlarged front elevational view of the assembly as shownin FIG. 83 showing the capture of the insert by opposed projections ofthe receiver.

FIG. 85 is an enlarged front elevational view with portions broken away,similar to FIG. 83, and further showing an enlarged and partial shank ofFIG. 59 in a first stage of assembly with the retainer, a hemisphere ofthe shank head and a vertebra portion both being shown in phantom.

FIG. 86 is a partial front elevational view with portions broken away,similar to FIG. 85, showing the retainer lower portion in an expandedstate about a mid-portion of the shank head, the head hemisphere shownin phantom.

FIG. 87 is a reduced partial front elevational view with portions brokenaway, similar to FIG. 86, the shank upper portion or head in frictionalengagement with an upper portion of the retainer.

FIG. 87A is an enlarged cross-sectional view taken along the line87A-87A of FIG. 87.

FIG. 88 is a partial front elevational view with portions broken away,similar to FIG. 87, the shank upper portion with attached retainer beingshown pulled down into a seated position within the lower receivercavity, the retainer spring tabs in a substantially neutral state,extending outwardly partially into receiver apertures.

FIG. 89 is an enlarged and partial front elevational view with portionsbroken away of all of the components shown in FIG. 59, the assembly asin FIG. 88 being shown in a stage of assembly with the rod and closuretop.

FIG. 90 is an enlarged and partial front elevational view with portionsbroken away, similar to FIG. 89, shown in a final locking position.

FIG. 91 is a reduced and partial front elevational view of the assemblyof FIG. 90.

FIG. 92 is an enlarged cross-sectional view taken along the line 92-92of FIG. 91.

FIG. 93 is an enlarged perspective view of an alternative locking insertfor use with the assembly of FIG. 59 in lieu of the insert shown in FIG.59.

FIG. 94 is a top plan view of the insert of FIG. 93.

FIG. 95 is a front elevational view of the insert of FIG. 93.

FIG. 96 is an enlarged front elevational view with portions broken awayof the receiver and retainer of FIG. 59 and the insert of FIG. 93 inreduced front elevation, the assembly shown in an un-locked shippingposition.

FIG. 97 is a reduced and partial front elevational view of the shank,receiver, retainer, rod and closure of FIG. 59, with portions brokenaway and assembled with the locking insert as shown in FIG. 96 in aninterim unlocked stage of assembly.

FIG. 98 is an enlarged and partial front elevational view of the shank,receiver, retainer, locking insert, rod and closure of FIG. 97, withportions broken away and shown in a final locked position.

FIG. 99 is an enlarged and partial front elevational view with portionsbroken away, similar to FIG. 98, showing the shank, retainer, insert andreceiver remaining in a locked position after removal of the rod andclosure top of FIG. 59 and further showing, in exploded view, analternative deformable rod and cooperating alternative closure top.

FIG. 100 is a partial front elevational view with portions broken away,similar to FIG. 99, showing the alternative rod and closure top fixed tothe remainder of the assembly.

FIG. 101 is a reduced and partial front elevational view with portionsbroken away of the assembly of FIG. 100 without the alternative rod andclosure top, and further showing unlocking of the insert from thereceiver with a two-piece tool having an inner insert engaging portionand an outer tubular holding portion.

FIG. 102 is a reduced and partial front elevational view of thetwo-piece tool of FIG. 101, holding prongs of the inner insert engagingportion being shown in phantom.

FIG. 103 is an enlarged and partial front elevational view of the innerinsert engaging portion of the tool shown in FIG. 102 with portionsbroken away to show the detail thereof.

FIG. 104 is an enlarged and partial perspective view of the assembly ofFIG. 97, but shown with the shank being at an angle with respect to thereceiver and further showing an alternative locking tool forindependently locking the insert into an interference fit with thereceiver and thus locking the shank with respect to the receiver evenwhen the closure top and rod are in a loose, unlocked relationship withthe receiver as shown.

FIG. 105 is an enlarged and partial perspective view of a portion of thelocking tool of FIG. 104.

FIG. 106 is an enlarged and partial front elevational view of theassembly and locking tool of FIG. 104 with portions broken away to showthe detail thereof.

DETAILED DESCRIPTION OF THE INVENTION

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention, which may be embodied in variousforms. Therefore, specific structural and functional details disclosedherein are not to be interpreted as limiting, but merely as a basis forthe claims and as a representative basis for teaching one skilled in theart to variously employ the present invention in virtually anyappropriately detailed structure. It is also noted that any reference tothe words top, bottom, up and down, and the like, in this applicationrefers to the alignment shown in the various drawings, as well as thenormal connotations applied to such devices, and is not intended torestrict positioning of the bone attachment structures in actual use.

With reference to FIGS. 1-37 the reference number 1 generally representsa polyaxial bone screw apparatus or assembly according to the presentinvention. The assembly 1 includes a shank 4, that further includes abody 6 integral with an upwardly extending upper portion or headstructure 8; a receiver 10; a friction fit retainer 12, and a crown-likecompression or pressure insert 14. The receiver 10, retainer 12 andcompression insert 14 are initially assembled and may be furtherassembled with the shank 4 either prior or subsequent to implantation ofthe shank body 6 into a vertebra 17, as will be described in greaterdetail below. FIGS. 1 and 36-37 further show a closure structure 18 forcapturing a longitudinal connecting member, for example, a rod 21 whichin turn engages the compression insert 14 that presses against the shankupper portion 8 into fixed frictional contact with the retainer 12, soas to capture, and fix the longitudinal connecting member 21 within thereceiver 10 and thus fix the member 21 relative to the vertebra 17. Theillustrated rod 21 is hard, stiff, non-elastic and cylindrical, havingan outer cylindrical surface 22. It is foreseen that in otherembodiments, the rod 21 may be elastic, deformable and/or of differentmaterials and cross-sectional geometries. The receiver 10 and the shank4 cooperate in such a manner that the receiver 10 and the shank 4 can besecured at any of a plurality of angles, articulations or rotationalalignments relative to one another and within a selected range of anglesboth from side to side and from front to rear, to enable flexible orarticulated engagement of the receiver 10 with the shank 4 until bothare locked or fixed relative to each other near the end of animplantation procedure.

The shank 4, best illustrated in FIGS. 1-3, is elongate, with the shankbody 6 having a helically wound bone implantable thread 24 (single ordual lead thread form and different thread types) extending from near aneck 26 located adjacent to the upper portion or head 8, to a tip 28 ofthe body 6 and extending radially outwardly therefrom. During use, thebody 6 utilizing the thread 24 for gripping and advancement is implantedinto the vertebra 17 leading with the tip 28 and driven down into thevertebra with an installation or driving tool (not shown), so as to beimplanted in the vertebra to a location at or near the neck 26, as morefully described in the paragraphs below. The shank 4 has an elongateaxis of rotation generally identified by the reference letter A.

The neck 26 extends axially upward from the shank body 6. The neck 26may be of the same or is typically of a slightly reduced radius ascompared to an adjacent upper end or top 32 of the body 6 where thethread 24 terminates. Further extending axially and outwardly from theneck 26 is the shank upper portion or head 8 that provides a connectiveor capture apparatus disposed at a distance from the upper end 32 andthus at a distance from the vertebra 17 when the body 6 is implanted insuch vertebra.

The shank upper portion 8 is configured for a pivotable connectionbetween the shank 4 and the retainer 12 and receiver 10 prior to fixingof the shank 4 in a desired position with respect to the receiver 10.The shank upper portion 8 has an outer, convex and substantiallyspherical surface 34 that extends outwardly and upwardly from the neck26 that in some embodiments terminates at a substantially planar top orrim surface 38. In the illustrated embodiment, a frusto-conical surface39 extends from the spherical surface 34 to the top surface 38,providing additional clearance during pivoting of the shank with respectto the receiver 10 and the insert 14. The spherical surface 34 has anouter radius configured for temporary frictional, non-floppy, slidingcooperation with panels of the retainer 12 having concave or flatsurfaces, as well as ultimate frictional engagement with the insert 14at an inner partially spherical surface thereof, as will be discussedmore fully in the paragraphs below. The top surface 38 is substantiallyperpendicular to the axis A. The spherical surface 34 shown in thepresent embodiment is substantially smooth, but in some embodiments mayinclude a roughening or other surface treatment and is sized and shapedfor cooperation and ultimate frictional engagement with the compressioninsert 14 as well as ultimate frictional engagement with a lowerring-like portion of the retainer 12. The shank spherical surface 34 islocked into place exclusively by the insert 14 and the retainer 12 lowerportion and not by inner surfaces defining the receiver cavity.

A counter sunk substantially planar base or stepped seating surface 45partially defines an internal drive feature or imprint 46. Theillustrated internal drive feature 46 is an aperture formed in the topsurface 38 and has a star shape designed to receive a tool (not shown)of an Allen wrench type, into the aperture for rotating and driving thebone screw shank 4. It is foreseen that such an internal tool engagementstructure may take a variety of tool-engaging forms and may include oneor more apertures of various shapes, such as a pair of spaced apartapertures or a multi-lobular or hex-shaped aperture. The seat or basesurfaces 45 of the drive feature 46 are disposed substantiallyperpendicular to the axis A with the drive feature 46 otherwise beingcoaxial with the axis A. As illustrated in FIGS. 2 and 3, the drive seat45 may include beveled or stepped surfaces that may further enhancegripping with the driving tool. In operation, a driving tool (not shown)is received in the internal drive feature 46, being seated at the base45 and engaging the faces of the drive feature 46 for both driving androtating the shank body 6 into the vertebra 17, either before the shank4 is attached to the receiver 10 or after the shank 4 is attached to thereceiver 10, with the shank body 6 being driven into the vertebra 17with the driving tool extending into the receiver 10.

The shank 4 shown in the drawings is cannulated, having a small centralbore 50 extending an entire length of the shank 4 along the axis A. Thebore 50 is defined by an inner cylindrical wall of the shank 4 and has acircular opening at the shank tip 28 and an upper opening communicatingwith the external drive 46 at the driving seat 45. The bore 50 iscoaxial with the threaded body 6 and the upper portion 8. The bore 50provides a passage through the shank 4 interior for a length of wire(not shown) inserted into the vertebra 17 prior to the insertion of theshank body 6, the wire providing a guide for insertion of the shank body6 into the vertebra 17. It is foreseen that the shank could be solid andmade of different materials, including metal and non-metals.

To provide a biologically active interface with the bone, the threadedshank body 6 may be coated, perforated, made porous or otherwisetreated. The treatment may include, but is not limited to a plasma spraycoating or other type of coating of a metal or, for example, a calciumphosphate; or a roughening, perforation or indentation in the shanksurface, such as by sputtering, sand blasting or acid etching, thatallows for bony ingrowth or ongrowth. Certain metal coatings act as ascaffold for bone ingrowth. Bio-ceramic calcium phosphate coatingsinclude, but are not limited to: alpha-tri-calcium phosphate andbeta-tri-calcium phosphate (Ca₃(PO₄)₂, tetra-calcium phosphate(Ca₄P₂O₉), amorphous calcium phosphate and hydroxyapatite(Ca₁₀(PO₄)₆(OH)₂). Coating with hydroxyapatite, for example, isdesirable as hydroxyapatite is chemically similar to bone with respectto mineral content and has been identified as being bioactive and thusnot only supportive of bone ingrowth, but actively taking part in bonebonding.

With particular reference to FIGS. 1 and 4-9, the receiver 10 has agenerally U-shaped appearance with partially discontinuous and partiallycylindrical inner and outer profiles. The receiver 10 has an axis ofrotation B that is shown in FIG. 1 as being aligned with and the same asthe axis of rotation A of the shank 4, such orientation being desirable,but not required during assembly of the receiver 10 with the shank 4.After the receiver 10 is pivotally attached to the shank 4, eitherbefore or after the shank 4 is implanted in a vertebra 17, the axis B istypically disposed at an angle with respect to the axis A, as shown, forexample, in FIG. 54.

The receiver 10 includes a substantially cylindrical base 60 defining abore or inner cavity, generally 61, the base 60 being integral with apair of opposed upstanding arms 62 forming a cradle and defining achannel 64 between the arms 62 with an upper opening, generally 66, anda U-shaped lower channel portion or seat 68, the channel 64 having awidth for operably snugly receiving the rod 21 or portion of anotherlongitudinal connector between the arms 62, the channel 64 communicatingwith the base cavity 61. Inner opposed substantially planar arm surfaces69 partially define the channel 64 directly above the seat 68 and arelocated on either side of each arm interior surface generally 70, thatincludes various inner cylindrical profiles, an upper one of which is apartial helically wound guide and advancement structure 72 locatedadjacent top surfaces 73 of each of the arms 62. In the illustratedembodiment, the guide and advancement structure 72 is a partialhelically wound interlocking flangeform configured to mate underrotation with a similar structure on the closure structure 18, asdescribed more fully below. However, it is foreseen that for certainembodiments of the invention, the guide and advancement structure 72could alternatively be a square-shaped thread, a buttress thread, areverse angle thread or other thread-like or non-thread-like helicallywound discontinuous advancement structures, for operably guiding underrotation and advancing the closure structure 18 downward between thearms 62, as well as eventual torquing when the closure structure 18abuts against the rod 21 or other longitudinal connecting member. It isforeseen that the arms 62 could have break-off extensions.

An opposed pair of upper rounded off triangular or delta-shaped toolreceiving and engaging apertures 74, each having a through bore formedby an upper arched surface 75 and a substantially planar bottom surface75′, are formed on outer surfaces 76 of the arms 62. Each through boresurface 75 and 75′ extends through the arm inner surface 70. Theapertures 74 with through bore portions 75 and 75′ are sized and shapedfor receiving portions of the retainer 12 during top loading of theretainer from the receiver opening 66 and into the base cavity 61 asshown, for example, in FIGS. 22-24 and as will be described in greaterdetail below. Each apertures 74 further includes a sloping toolalignment surface 77 that surrounds the arched bore portion 75 and doesnot extend completely through the respective arm 62. Thin edge portions77A and 77B of the sloping surface 77 also function as a crimp wall thatis pressed or crimped into the insert 14 to prohibit rotation andmisalignment of the insert 14 with respect to the receiver 10 as will bedescribed in greater detail below. In other embodiments of theinvention, other surfaces forming the aperture 74 may be inwardlycrimped. The receiver 10 is an integral structure and devoid of anyspring tabs or collet-like structures. Preferably the insert and/orreceiver are configured with structure for blocking rotation of theinsert with respect to the receiver, such as the sloping crimp wall 77,but allowing some up and down movement of the insert with respect to thereceiver during the assembly and implant procedure. Two additionalrectangular shaped through bores 78 are also formed in the arms 62 andare located directly below the apertures 74. It is foreseen that theopening 78 could assume almost any shape. The through bores 78 are sizedand shaped for receiving spring tab portions of the retainer 12 duringassembly and final operation and which capture and retain the retainer12 within the receiver as shown, for example, in FIG. 26. An uppersurface 79 defining each bore 78 functions as an upper stop for aportion of the retainer 12, during shipping and during assembly as willbe described in greater detail below. Also formed in each outer armsurface 76 near the top surface 73 is an undercut tool receiving andengaging groove 81. Some or all of the apertures 74 and 78 and thegroove 81 may be used for holding the receiver 10 during assembly withthe insert 14, the retainer 12 and the shank 4; during the implantationof the shank body 6 into a vertebra when the shank is pre-assembled withthe receiver 10; during assembly of the bone anchor assembly 1 with therod 21 and the closure structure 18; and during lock and releaseadjustment of some inserts according to the invention with respect tothe receiver 10, either into or out of frictional engagement with theinner surfaces of the receiver 10 as will be described in greater detailbelow. It is foreseen that tool receiving grooves or apertures may beconfigured in a variety of shapes and sizes and be disposed at otherlocations on the receiver arms 62.

Returning to the interior surface 70 of the receiver arms 62, locatedbelow the guide and advancement structure 72 is a discontinuouscylindrical surface 82 partially defining a run-out feature for theguide and advancement structure 72. The cylindrical surface 82 has adiameter equal to or slightly greater than a greater diameter of theguide and advancement structure 72. Moving downwardly, in a directiontoward the base 60, following the cylindrical surface 82 of each arm isa cylindrical surface (or, in some embodiments, a tapered surface) 88located below an annular run-out seat or surface 85 that extendsinwardly toward the axis B and runs perpendicular or somewhat obliquelytowards the axis B. The surface 88 has a diameter smaller than thediameter of the surface 82. The surface 88 is sized and shaped toinitially closely receive a portion of the insert 14. A discontinuousannular surface or narrow ledge 89 is located below the surface 88 andis substantially perpendicular to the axis B. A partially discontinuouscylindrical surface 90 is located on each arm below and adjacent to thesurface 89. The surface 90 also defines an upper cylindrical surface ofthe base cavity 61. The surface 90 has a diameter slightly smaller thanthe diameter of the surface 88. It is noted that in some embodiments ofthe invention, the surfaces 88 and 90 are combined and form a singlecylindrical surface.

The through bores 75 of the apertures 74 each extend through the arms atthe surfaces 82 and 88 with the sloping tool engagement and crimp walls77 extending substantially on either side of each bore surface 75 andformed in the arm outer surfaces 76 at a location opposite the innersurfaces 82 and 88. Thus, portions of the surfaces 88 are pressed intoengagement with the insert 14 when the thin, deformable edge portions ofthe walls 77 are pressed toward the insert 14 as will be described ingreater detail below. With reference to FIG. 30, the crimp wall portionsthat are pressed into engagement with the insert 14 are identified as77A and 77B. It is foreseen that the crimp wall portions could be in theform of deformable crimp tabs.

Returning to FIGS. 8 and 9, an annular surface 98 partially defining thebase cavity 61 and is located below and adjacent to the cylindricalsurface 90. The surface 98 is disposed substantially perpendicular tothe axis B, but could be oblique. Another cylindrical surface 99 islocated below and adjacent to the surface 98. The cylindrical surface 99is oriented substantially parallel to the axis B and is sized and shapedto receive an expanded portion of retainer 12. The surfaces 98 and 99define a circumferential recess that is sized and shaped to receive theretainer 12 as it expands around the shank upper portion 8 as the shank8 moves upwardly toward the channel 64 during assembly. It is foreseenthat the recess could be tapered or conical in configuration. Acylindrical surface 101 located below the cylindrical surface 99 issized and shaped to closely receive and surround a lower portion of theretainer 12 when the retainer is in a substantially neutral position asshown in FIG. 28, for example. Thus, the cylindrical surface 101 has adiameter smaller than the diameter of the cylindrical surface 99 thatdefines the expansion area or expansion chamber for the retainer 12. Thesurface 101 is joined or connected to the surface 99 by one or morebeveled, curved or conical surfaces 102. The surfaces 102 allow forsliding and neutral or nominal positioning of the retainer 12 into thespace defined by the surface 101 and ultimate seating of the retainer 12on a lower substantially horizontal annular surface 104 located belowand adjacent to the cylindrical surface 101.

Located below and adjacent to the annular seating surface 104 is anothersubstantially cylindrical surface 106 that communicates with a beveledor flared bottom opening surface 107, the surface 107 communicating withan exterior base surface 108 of the base 60, defining a lower opening,generally 110, into the base cavity 61 of the receiver 10.

With particular reference to FIGS. 1 and 10-15, the lower open or splitfriction fit retainer 12, that operates to capture the shank upperportion 8 within the receiver 10, has a central axis that isoperationally the same as the axis B associated with the receiver 10when the shank upper portion 8 and the retainer 12 are installed withinthe receiver 10. The retainer 12 includes a substantially cylindricaldiscontinuous lower body 116, a plurality of flex fingers or panels, 117extending upwardly from the body 116 and a pair of opposed spring armsor tabs 118, also extending upwardly from the body 116. The retainerring 12 is made from a resilient material, such as a stainless steel ortitanium alloy, so that the retainer 12 body 116 may be expanded and thefingers and tabs (117 and 118) of the retainer may be manipulated duringvarious steps of assembly as will be described in greater detail below.The retainer 12 has a central channel or hollow through bore, generally121, that passes entirely through the retainer 12 from tab 118 topsurfaces 122 to a bottom surface 124 of the retainer body 116. Surfacesthat define the channel or bore 121 at the body 116 include an innerlower frusto-conical surface 128 adjacent to the retainer body bottomsurface 124, a substantially cylindrical surface 130 adjacent thefrusto-conical surface 128 and a partially continuous partiallydiscontinuous substantially spherical surface 132 located adjacent thecylindrical surface 130, the surface 132 being substantially continuousnear the surface 130 and at each of the spring tabs 118 and otherwisebroken by a through slot or slit, generally 134 and a plurality ofevenly spaced partial slots or grooves 136. The grooves 136 separate thesurface 132 into a plurality of segments or pieces that have alreadybeen described herein as the flex fingers 117. The grooves or slots 136run outwardly and upwardly from the retainer body 116 through an uppersurface 137 of the retainer 12 located between the spring tabs 118. Inthe illustrated embodiment, the slots 136 and the through slit 134 formthe six substantially uniform flex fingers or tabs 117 as well aspartially define the two spring tabs 118, each finger 117 having theinner spherical surface 132 while each of the spring tabs 118 extendoutwardly and away from the surface 132 at the retainer body 116. It isforeseen that more or fewer flex fingers may be made by the forming ofmore or fewer slots 136 and that the surface 132 could be planar,tapered, faceted or otherwise curved. The illustrated discontinuousspherical surface 132 is sized and shaped to closely fit about and snaponto the shank surface 34 during assembly as will be described ingreater detail below. Preferably the surface 132 has a radius the same,slightly smaller or slightly larger than the radius of the sphericalshank surface 34. The surface 132 could be bent or deformed inwardly oroutwardly to better cooperate with the shank head. In operation, thediscontinuous surface 132 advantageously frictionally engages the bonescrew shank upper portion or head 8, allowing for an un-locked frictionfit, non-floppy placement of the angle of the shank 4 with respect tothe receiver 10 during surgery prior to locking of the shank 4 withrespect to the receiver 10 near the end of the procedure. At the time oflocking engagement, as shown in FIG. 37, for example, downward andoutward force placed on the retainer 12 by the shank upper portion 8expands the retainer body 116 at the slit 134 and the individual flexfingers 117 no longer frictionally grip the spherical head surface 34 ofthe upper portion 8. To aid in bending flexibility and resiliency, someor all of the flex fingers 117 may have sloping outer surfaces or othergeometry to gain the level of resiliency desired for expansion andgripping of the fingers 117 about the shank upper portion 8. Forexample, the illustrated fingers 117 each include an outer bevel 138.The spherical surfaces 132 may include a surface treatment or rougheningto provide a desired friction fit. Again, it is noted that the surfaces132 need not be spherical and may be planar or include other surfacegeometries that resiliently grip the shank upper portion or head 8.Again, in some embodiments, the flexible tabs 117 may be bent ordeformed to further enhance frictional engagement. It is noted that thefingers 117 that are directed generally upwardly toward the receiverchannel 64 advantageously sufficiently snap about and then grip theshank surface 34 to an extent to provide the friction fit desired fornon-floppy placement of the shank body 6 at a desired angle with respectto the receiver 10 during manipulation of the bone screws 1 and the rod21 or other longitudinal connecting member during surgery. However, ascompared to bone screw inserts such as collets known in the art thatinclude downwardly directed portions or panels that are ultimatelywedged between a receiver surface and a shank surface upon final lockingof the shank to the receiver, the thin upwardly directed fingers 117that extend away from the shank locking surface that are not as strongas the retainer body 116 or the insert 114, do not participate orcooperate with the final locking of the insert 114 to the shank upperportion 8, the shank upper portion 8 to the retainer 12, and theretainer 12 to the receiver inner and substantially planar surfaces 101and 104. For such purpose, the more substantial retainer body 116located below the slots 136 having only the very narrow slit 134, usedfor expansion purposes only, is the component or portion that locks theshank upper portion 8 between the receiver 10, the insert 114 and therod 21 or other longitudinal connecting member.

The retainer body 116 and the flex fingers 117 have an outersubstantially cylindrical profile, sized and shaped to closely andslidingly fit within the receiver cavity 61. The opposed pair of springtabs 118, however, extend outwardly away from one another and thusoutwardly from the body 116. Each spring tab 118 is sized and shaped toclosely cooperate and frictionally engage upper surfaces 79 defining thethrough bores 78. An outer surface 143 of each spring tab 118 locatedadjacent each upper surface 122 is sized and shaped to cooperate withand frictionally engage the cylindrical surface 90 during assembly andshipping as shown, for example, in FIG. 31. In some embodiments of theinvention, the tab 118 surface 143 may include one or more projections,grooves or notches as needed for tooling to resiliently hold theretainer in an upper portion of the cavity 61 when desired, but readilyrelease the retainer 12 into a lower portion of the receiver cavity 61once the retainer flex tabs 117 engage the shank head 8. The illustratedspring tabs 118 each include one or more planar or curved concave innersurfaces 144 running from the top surface 122 to a tab base seat,surface or surfaces 145 located adjacent to and running laterallyoutwardly from the surface 132. The surfaces 144 extend both outwardlyand upwardly from the base seat surfaces 145. It is foreseen that inother embodiments of the invention, fewer or greater number of planar orother surfaces with other geometries may extend between the top surface122 and the inner surfaces defining the body 116 of the retainer 12.

The through slit 134 of the resilient retainer 12 is defined by firstand second end surfaces, 146 and 147 disposed in spaced relation to oneanother (they may also be touching) when the retainer is in a neutralstate. Both end surfaces 146 and 147 are disposed substantiallyperpendicular to the bottom surface 124. A width X between the surfaces146 and 147 is very narrow (slit may be made by EDM process) to providestability to the retainer 12 during operation. Because the retainer 12is top loadable in a neutral state and the retainer 12 does not need tobe compressed to fit within the receiver cavity 61, the width X may bemuch smaller than might be required for a bottom loaded compressibleretainer ring. The gap X functions only in expansion to allow theretainer 12 to expand about the shank upper portion 8. This results in astronger retainer that provides more surface contact with the shankupper portion 8 upon locking, resulting in a sturdier connection withless likelihood of failure than a retainer ring having a greater gap.Furthermore, because the retainer 12 body 116 is only expanded and nevercompressed inwardly, the retainer 12 does not undergo the mechanicalstress that typically is placed on spring ring type retainers known inthe prior art that are both compressed inwardly and expanded outwardlyduring assembly.

It is foreseen that in some embodiments of the invention, the retainer12 inner surfaces may include a roughening or additional material toincrease the friction fit against the shank upper portion 8 prior tolock down by the rod 21 or other longitudinal connecting member. Also,the embodiment shown in FIGS. 10-15 illustrates the surfaces 146 and 147as substantially parallel, however, it is foreseen that it may bedesirable to orient the surfaces obliquely or at a slight angle.

With particular reference to FIGS. 1 and 16-21, the compression insert14 is illustrated that is sized and shaped to be received by anddown-loaded into the receiver 10 at the upper opening 66. Thecompression insert 14 has an operational central axis that is the sameas the central axis B of the receiver 10. In operation, the insertadvantageously frictionally engages the bone screw shank upper portion8. As will be described in greater detail below with respect to theinsert 214, in some embodiments of the invention, the insert that haslocked the shank 4 in a desired angular position with respect to thereceiver 10, by, for example, compression from the rod 21 and closuretop 18, is also forced into an interference fit engagement with thereceiver 10 at an outer cylindrical surface thereof and thus is capableof retaining the shank 6 in a locked position even if the rod 21 andclosure top 18 are removed. Such locked position may also be released bythe surgeon if desired. The non-locking insert 14 as well as the lockinginsert 214 are preferably made from a solid resilient material, such asa stainless steel or titanium alloy, so that portions of the insert maybe pinched and un-wedged from the receiver 10 with a release tool.

The non-locking compression insert 14 includes a substantiallycylindrical body 156 integral with a pair of upstanding arms 157. Abore, generally 160, is disposed primarily within and through the body156 and communicates with a generally U-shaped through channel 161 thatis defined by the upstanding arms 157. The channel 161 has a lower seat162 sized and shaped to closely, snugly engage the rod 21. It isforeseen that an alternative embodiment may be configured to includeplanar holding surfaces that closely hold a square or rectangular bar aswell as hold a cylindrical rod-shaped, cord, or sleeved cordlongitudinal connecting member. The arms 157 disposed on either side ofthe channel 141 extend upwardly and outwardly from the body 156. Thearms 157 are sized and configured for ultimate placement beneath thecylindrical run-out surface 82 located below the receiver guide andadvancement structure 72. It is foreseen that in some embodiments of theinvention, the arms may be extended and the closure top configured suchthat the arms and, more specifically, the surfaces 164 ultimatelydirectly engage the closure top 18 for locking of the polyaxialmechanism, for example, when the rod 21 is made from a deformablematerial. In such embodiments, the insert 14 would include a rotationblocking structure or feature that abuts against cooperating structurelocated on an inner wall of the receiver 10, preventing rotation of theinsert with respect to the receiver when the closure top is rotated intoengagement with the insert. In the present embodiment, the arms 157include upper outer cylindrical surfaces 163 and top surfaces 164 thatare ultimately positioned in spaced relation with the closure top 18, sothat the closure top 18 frictionally engages the rod 21 only, pressingthe rod 21 downwardly against the seating surface 162, the insert 14 inturn pressing against the shank 4 upper portion 8 that presses againstthe retainer 12 to lock the polyaxial mechanism of the bone screwassembly 1 at a desired angle.

The bore, generally 160, is substantially defined at the body 156 by aninner cylindrical surface 166 that communicates with the seat 162 and alower concave substantially spherical surface 168 having a radius thesame or substantially similar to a radius of the surface 34 of the shankupper portion 8. The surface 168 terminates at an annular andsubstantially planar base surface 169 of the body 156. Located betweenthe cylindrical surface 166 and the spherical surface 168 or locatedalong the spherical surface 168 is a shank gripping surface portion,generally 170. The gripping surface portion 170 includes one or morestepped surfaces or ridges sized and shaped to grip and penetrate intothe shank head 8 when the insert 14 is locked against the head surface34. It is foreseen that the stepped surface portion 170 may includegreater or fewer number of stepped surfaces. It is foreseen that theshank gripping surface portion 170 and also the spherical surface 168may additionally or alternatively include a roughened or texturedsurface or surface finish, or may be scored, knurled, or the like, forenhancing frictional engagement with the shank upper portion 8.

The compression insert 14 through bore 160 is sized and shaped toreceive the driving tool (not shown) therethrough that engages the shankdrive feature 46 when the shank body 6 is driven into bone with thereceiver 10 attached. Also, in some locking embodiments of theinvention, the bore receives a manipulation tool (not shown) used forreleasing the insert from a locked position with the receiver, the toolpressing down on the shank and also gripping the insert at through boreslocated in the arms or with other tool engaging features. For example, amanipulation tool for releasing the insert from the receiver 10 may alsoaccess such bores from the receiver through the apertures 74 in thereceiver. Thereby, tools can be configured to release a locking insertfrom the inside and outside of the receiver 10.

The illustrated insert 14 further includes an outer lower arm surface174 adjacent to the upper arm outer surface 164 and having a radiusslightly smaller than a radius of the upper arm surfaces 163. The armsurfaces 163 further include notches or grooves formed thereon. In theillustrated embodiments, each surface 163 includes a pair of spacedv-notches or grooves 175A and 175B that run from the respective topsurface 164 to the respective lower arm surface 174. The grooves 175cooperate with the receiver crimp walls 77 to aid in alignment of theinsert channel 161 with the receiver channel 64. Each lower arm surface174 runs from the mid-point or location of the arm to the insert bottomsurface 169. Each surface includes a recessed area or portion 178 sizedand shaped to receive and allow clearance for the upper surface 122 ofthe retainer spring tabs 118, as shown, for example, in FIG. 31, duringassembly and shipping of the pre-assembled receiver 10, retainer 12 andinsert 14. Adjacent each recessed area or portion 178 is a bevel or flatsurface 179 cut into the lower outer surface 174 near the base or bottomsurface 169. Thus, there are two surfaces 179 located on either side ofthe insert 14 at opposite sides thereof. As best shown in FIGS. 27-29,and described in greater detail below, the surfaces 170 allow forclockwise rotation of the insert 14 into place within the receiver, thebevel or flat 179 allowing clearance between the insert 14 and theretainer spring tab 118 during rotation into place. Once the insert 14is in the desired position within the receiver, the insert surfacelocated adjacent the recess 178 that is not beveled, identified by thereference number 180, prohibits further rotation of the insert as bestshown, for example, in FIG. 29.

The insert body 156 has an outer diameter slightly smaller than adiameter between crests of the guide and advancement structure 72 of thereceiver 10, allowing for top loading of the compression insert 14 intothe receiver opening 66, with the arms 157 of the insert 14 beinglocated between the receiver arms 62 during insertion of the insert 14into the receiver 10. Once the arms 157 of the insert 14 are generallylocated beneath the guide and advancement structure 72, the insert 14 isrotated in a clockwise direction K into place about the receiver axis Buntil the top surfaces 164 are located directly below the guide andadvancement structure 72 as will be described in greater detail below.The insert outer arm surfaces 174 are sized and shaped to be slidinglyreceived by the receiver surface 90 during final locking of the assembly1.

With reference to FIGS. 1 and 36-37, the illustrated elongate rod orlongitudinal connecting member 21 (of which only a portion has beenshown) can be any of a variety of implants utilized in reconstructivespinal surgery, but is typically a cylindrical, elongate structurehaving the outer substantially smooth, cylindrical surface 22 of uniformdiameter. The rod 21 may be made from a variety of metals, metal alloys,non-metals and deformable and less compressible plastics, including, butnot limited to rods made of elastomeric, polyetheretherketone (PEEK) andother types of materials, such as polycarbonate urethanes (PCU) andpolyethylenes.

Longitudinal connecting members for use with the assembly 1 may take avariety of shapes, including but not limited to rods or bars of oval,rectangular or other curved or polygonal cross-section. The shape of theinsert 14 may be modified so as to closely hold the particularlongitudinal connecting member used in the assembly 1. Some embodimentsof the assembly 1 may also be used with a tensioned cord. Such a cordmay be made from a variety of materials, including polyester or otherplastic fibers, strands or threads, such as polyethylene-terephthalate.Furthermore, the longitudinal connector may be a component of a longeroverall dynamic stabilization connecting member, with cylindrical orbar-shaped portions sized and shaped for being received by thecompression insert 14 of the receiver having a U-shaped, rectangular- orother-shaped channel, for closely receiving the longitudinal connectingmember. The longitudinal connecting member may be integral or otherwisefixed to a bendable or damping component that is sized and shaped to belocated between adjacent pairs of bone screw assemblies 1, for example.A damping component or bumper may be attached to the longitudinalconnecting member at one or both sides of the bone screw assembly 1. Arod or bar (or rod or bar component) of a longitudinal connecting membermay be made of a variety of materials ranging from deformable plasticsto hard metals, depending upon the desired application. Thus, bars androds of the invention may be made of materials including, but notlimited to metal and metal alloys including but not limited to stainlesssteel, titanium, titanium alloys and cobalt chrome; or other suitablematerials, including plastic polymers such as polyetheretherketone(PEEK), ultra-high-molecular weight-polyethylene (UHMWP), polyurethanesand composites, including composites containing carbon fiber, natural orsynthetic elastomers such as polyisoprene (natural rubber), andsynthetic polymers, copolymers, and thermoplastic elastomers, forexample, polyurethane elastomers such as polycarbonate-urethaneelastomers.

With reference to FIGS. 1 and 36-37, the closure structure or closuretop 18 shown with the assembly 1 is rotatably received between thespaced arms 62 of the receiver 10. It is noted that the closure 18 topcould be a twist-in or slide-in closure structure. The illustratedclosure structure 18 is substantially cylindrical and includes a anouter helically wound guide and advancement structure 182 in the form ofa flange that operably joins with the guide and advancement structure 72disposed on the arms 62 of the receiver 10. The flange form utilized inaccordance with the present invention may take a variety of forms,including those described in Applicant's U.S. Pat. No. 6,726,689, whichis incorporated herein by reference. Although it is foreseen that theclosure structure guide and advancement structure could alternatively bea buttress thread, a square thread, a reverse angle thread or otherthread like or non-thread like helically wound advancement structure,for operably guiding under rotation and advancing the closure structure18 downward between the arms 62 and having such a nature as to resistsplaying of the arms 62 when the closure structure 18 is advanced intothe channel 64, the flange form illustrated herein as described morefully in Applicant's U.S. Pat. No. 6,726,689 is preferred as the addedstrength provided by such flange form beneficially cooperates with andcounters any reduction in strength caused by the any reduced profile ofthe receiver 10 that may more advantageously engage longitudinalconnecting member components. The illustrated closure structure 18 alsoincludes a top surface 184 with an internal drive 186 in the form of anaperture that is illustrated as a star-shaped internal drive such asthat sold under the trademark TORX, or may be, for example, a hex drive,or other internal drives such as slotted, tri-wing, spanner, two or moreapertures of various shapes, and the like. A driving tool (not shown)sized and shaped for engagement with the internal drive 186 is used forboth rotatable engagement and, if needed, disengagement of the closure18 from the receiver arms 62. It is also foreseen that the closurestructure 18 may alternatively include a break-off head designed toallow such a head to break from a base of the closure at a preselectedtorque, for example, 70 to 140 inch pounds. Such a closure structurewould also include a base having an internal drive to be used forclosure removal. A base or bottom surface 188 of the closure is planarand further includes a point 189 and a rim 190 for engagement andpenetration into the surface 22 of the rod 21 in certain embodiments ofthe invention. It is noted that in some embodiments, the closure topbottom surface 188 does not include the point and/or the rim. Theclosure top 18 may further include a cannulation through bore (notshown) extending along a central axis thereof and through the top andbottom surfaces thereof. Such a through bore provides a passage throughthe closure 18 interior for a length of wire (not shown) insertedtherein to provide a guide for insertion of the closure top into thereceiver arms 62.

An alternative closure top 218 for use with a deformable rod, such as aPEEK rod 221, is shown in FIGS. 49 and 50. The top 218 is identical tothe top 18 with the exception that a point or nub 289 is located on adomed surface 290 in lieu of the point and rim of the closure top 18.The closure top 218 otherwise includes a guide and advancement structure282, a top 284, an internal drive 286 and a bottom outer rim surface 288that same or substantially similar to the guide and advancementstructure 182, top 184, internal drive 186 and a bottom surface 188described herein with respect to the closure top 18. In someembodiments, the internal drive 286 is not as large as the drive 186 ofthe closure top 18, such smaller drive providing for less force beingplaced on a deformable rod, for example, and not being required when alocking insert, for example, the insert 218 discussed below is utilizedin a bone screw assembly of the invention.

Returning to the assembly 1, preferably, the receiver 10, the retainer12 and the compression insert 14 are assembled at a factory setting thatincludes tooling for holding and alignment of the component pieces andpinching or compressing of the retainer 12 spring tabs 118 and rotatingand otherwise manipulating the insert 14 arms, as well as crimping aportion of the receiver 10 toward the insert 14. In some circumstances,the shank 4 is also assembled with the receiver 10, the retainer 12 andthe compression insert 14 at the factory. In other instances, it isdesirable to first implant the shank 4, followed by addition of thepre-assembled receiver, retainer and compression insert at the insertionpoint. In this way, the surgeon may advantageously and more easilyimplant and manipulate the shanks 4, distract or compress the vertebraewith the shanks and work around the shank upper portions or headswithout the cooperating receivers being in the way. In other instances,it is desirable for the surgical staff to pre-assemble a shank of adesired size and/or variety (e.g., surface treatment of roughening theupper portion 8 and/or hydroxyapatite on the shank 6), with thereceiver, retainer and compression insert. Allowing the surgeon tochoose the appropriately sized or treated shank 4 advantageously reducesinventory requirements, thus reducing overall cost and improvinglogistics and distribution.

Pre-assembly of the receiver 10, retainer 12 and compression insert 14is shown in FIGS. 22-31. With particular reference to FIG. 22, first theretainer 12 is inserted into the upper receiver opening 66, leading withone of the spring tabs 118 with both of the spring tab top surfaces 122facing one arm 62 and the retainer bottom surface 124 facing theopposing arm 62 (shown in phantom). The retainer 12 is then lowered insuch sideways manner into the channel 64 and partially into the receivercavity 61, followed by tilting the retainer 12 such that the top surface122 and thereafter the top surface 122 of the leading spring tab 118 ismoved into a nearby receiver arm aperture 74 below the arched throughbore surface 75. With reference to FIG. 23, the retainer 12 is thenfurther tilted or turned and manipulated within the receiver to aposition within the cavity until the retainer 12 bottom surface 124 isdirected toward the receiver cavity 61 and the spring tab upper surfaces122 are facing upwardly toward the receiver channel opening 66 as shownin FIG. 24. To accomplish such tilting and turning of the retainer 12,the spring tab arm 118 located within the receiver bore surface 75 ismanipulated downwardly and then upwardly within such bore and finallyshifted out of such bore when the opposed spring tab arm 118 moves pastand clears the guide and advancement structure 72 of the receiver 10.With further reference to FIG. 24 and also FIG. 25, the retainer 12 ismoved downwardly toward the receiver base 60 and the spring tabs 118 arepressed resiliently toward one another as the retainer spring taboutside surfaces 143 abut against the receiver cylindrical surfaces 90.With reference to FIG. 26, once the retainer bottom surface 124 seats onthe receiver surface 104, the spring tab surfaces 143 clear the surface90 and the tabs spring back out to a substantially neutral position withportions of the top surfaces 122 of each of the spring tabs 118 beinglocated beneath the surfaces 79 of the through bores 78. At this time,the retainer 12 is captured within the receiver base cavity 61 unlessthe spring tabs 118 are squeezed toward one another so as to clear thethrough bores 78.

With reference to FIG. 27, the compression insert 14 is then downloadedinto the receiver 10 through the upper opening 66 with the bottomsurface 169 facing the receiver arm top surfaces 73 and the insert arms157 located between the opposed receiver arms 62. The insert 14 is thenlowered toward the receiver base 60 until the insert 14 arm uppersurfaces 164 are adjacent the run-out area below the guide andadvancement structure 72 defined in part by the cylindrical surface 82.Thereafter, the insert 14 is rotated in a clockwise manner (see thearrow K) about the receiver axis B until the upper arm surfaces 164 aredirectly below the guide and advancement structure 72 as illustrated inFIG. 28 with the U-shaped channel 161 of the insert 14 aligned with theU-shaped channel 64 of the receiver 10. In some embodiments, the insertarms 157 may need to be compressed slightly during rotation to clearinner surfaces of the receiver arms 62. As shown in FIGS. 27-29, thebevel or flat 179 at the base of the arm portion 157 is initiallyreceived within one of the receiver arms 62 when the clock-wise rotationis begun, the flat 179 clearing the retainer spring tab 118 duringrotation. However, as there is no such flat surface on the other side ofthe recess or aperture 178, the surface 180 partially defining therecess 178 abuts against the spring tab 118 at a desirable locationwherein the insert U-shaped channel 161 is aligned with the receiverchannel 64. This is best seen in FIG. 29. With reference to FIG. 30,thereafter, a pair of crimps 77A and 77B are made in the receiversurface 77, the crimps 77A and 77B are pressed toward the insert 14 atrespective grooves 175A and 175B. The, crimped portions 77A and 77B helpretain the desired alignment between the insert 14 and the receiver 10and prohibit relative rotation between the two parts. However, relativevertical movement between the insert 14 and the receiver 10 is possibleas the crimps do not vertically fix the insert with respect to thereceiver.

With further reference to FIG. 31, a tool (not shown) is then used togrip the retainer spring tab arms 118 at outer surfaces 143 thereof andsqueeze or press the tabs 118 toward one another while moving theretainer 12 in an upward direction away from the surface 104. When thespring tab surfaces 143 are located within the cylindrical surface 90and are partially received in the insert recesses 178, the tool (notshown) is released and a portion of the surface 143 of each spring tab118 spring out to engage the surface portion 90. The retainer 12 and theinsert 14 are now in a desired position for shipping as an assemblyalong with the separate shank 4. The insert 14 recessed areas 178 arenow located adjacent to the retainer spring tab top surfaces 122. Theinsert 14 is fully captured within the receiver 10 by the guide andadvancement structure 72 prohibiting movement of the insert 14 up andout through the receiver opening 66 as well as by retainer 12 locatedbelow the insert.

Typically, the receiver and retainer combination are shipped orotherwise provided to the end user with the spring tabs 118 wedgedagainst the receiver as shown in FIG. 31. The receiver 10, retainer 12and insert 14 combination is now pre-assembled and ready for assemblywith the shank 4 either at the factory, by surgery staff prior toimplantation, or directly upon an implanted shank 4 as will be describedherein.

As illustrated in FIG. 32, the bone screw shank 4 or an entire assembly1 made up of the assembled shank 4, receiver 10, retainer 12 andcompression insert 14, is screwed into a bone, such as the vertebra 17(shown in phantom), by rotation of the shank 4 using a suitable drivingtool (not shown) that operably drives and rotates the shank body 6 byengagement thereof at the internal drive 46. Specifically, the vertebra17 may be pre-drilled to minimize stressing the bone and have a guidewire (not shown) inserted therein to provide a guide for the placementand angle of the shank 4 with respect to the vertebra. A further taphole may be made using a tap with the guide wire as a guide. Then, thebone screw shank 4 or the entire assembly 1 is threaded onto the guidewire utilizing the cannulation bore 50 by first threading the wire intothe opening at the bottom 28 and then out of the top opening at thedrive feature 46. The shank 4 is then driven into the vertebra using thewire as a placement guide. It is foreseen that the shank and other bonescrew assembly parts, the rod 21 (also having a central lumen in someembodiments) and the closure top 18 (also with a central bore) can beinserted in a percutaneous or minimally invasive surgical manner,utilizing guide wires and attachable tower tools mating with thereceiver. When the shank 4 is driven into the vertebra 17 without theremainder of the assembly 1, the shank 4 may either be driven to adesired final location or may be driven to a location slightly above orproud to provide for ease in assembly with the pre-assembled receiver,compression insert and retainer.

With further reference to FIG. 32, the pre-assembled receiver, insertand retainer are placed above the shank upper portion 8 until the shankupper portion is received within the opening 110. With particularreference to FIGS. 32, 33 and 34, as the shank upper portion 8 is movedinto the interior 61 of the receiver base, the shank upper portion 8presses upwardly against the retainer 12 in the recess partially definedby the cylindrical surface 99. As the portion 8 continues to moveupwardly toward the channel 64, the surface 34 forces outward movementof the retainer 12 towards the cylindrical surface 99 defining thereceiver expansion recess or chamber as shown in FIG. 33. With referenceto FIG. 34, the retainer 12 begins to return to its neutral state as thecenter of the sphere (shown in dotted lines) passes beyond the center ofthe retainer expansion recess. At this time also, the spherical surface34 moves into engagement with the surfaces 132 of the retainer flex tabs117, the tabs 117 expanding slightly outwardly to receive the surface34. With further reference to FIG. 34, the spherical surface 34 thenenters into full frictional engagement with the panel inner surfaces132. At this time, the retainer 12 panels and the surface 34 are in afairly tight friction fit, the surface 34 being pivotable with respectto the retainer 12 with some force. Thus, a tight, non-floppy ball andsocket joint is now created between the retainer 12 and the shank upperportion 8.

With reference to FIG. 35, the receiver is then pulled upwardly or theshank 4 and attached retainer 12 are then moved downwardly into adesired position with the retainer seated on the surface 104. Again,this may be accomplished by either an upward pull on the receiver 10 or,in some cases, by driving the shank 4 further into the vertebra 17. Atthis time, the retainer spring tabs 118 once against spring outwardlyinto the receiver bores 78, making it impossible to move the retainerout of the locking portion of the chamber defined in part by thereceiver seat 104 unless pressed inwardly by a tool or tools via thethrough bores 78. With reference to FIG. 36, the insert 14 may bepressed downwardly by a tool or by the rod 21 and the closure top 18.Also, in some embodiments, when the receiver 10 is pre-assembled withthe shank 4, the entire assembly 1 may be implanted at this time byinserting the driving tool (not shown) into the receiver and the shankdrive 46 and rotating and driving the shank 4 into a desired location ofthe vertebra 17.

With reference to FIG. 36 and also, for example, to FIG. 54 (that showsthe use of the assembly 1 with an alternative insert), at this time, thereceiver 10 may be articulated to a desired angular position withrespect to the shank 4, such as that shown in FIG. 54, that will beheld, but not locked, by the frictional engagement between the retainer12 and the shank upper portion 8.

With further reference to FIGS. 36 and 37, the rod 21 is eventuallypositioned in an open or percutaneous manner in cooperation with the atleast two bone screw assemblies 1. The closure structure 18 is thenadvanced between the arms 62 of each of the receivers 10. The closurestructure 18 is rotated, using a tool engaged with the inner drive 186until a selected pressure is reached at which point the rod 21 engagesthe U-shaped seating surface 162 of the compression insert 14, furtherpressing the insert spherical surface 168 and stepped shank grippingsurfaces 170 against the shank spherical surface 34, the edges of thestepped surfaces 170 penetrating into the spherical surface 34, pressingthe shank upper portion 8 into locked frictional engagement with theretainer 12. Specifically, as the closure structure 18 rotates and movesdownwardly into the respective receiver 10, the point 189 and rim 190engage and penetrate the rod surface 22, the closure structure 18pressing downwardly against and biasing the rod 21 into compressiveengagement with the insert 14 that urges the shank upper portion 8toward the retainer 12 and into locking engagement therewith, theretainer 12 frictionally abutting the surface 104 and expandingoutwardly against the cylindrical surface 101. For example, about 80 toabout 120 inch pounds of torque on the closure top may be applied forfixing the bone screw shank 6 with respect to the receiver 10. Ifdisassembly if the assembly 1 is desired, such is accomplished inreverse order to the procedure described previously herein for assembly.

With reference to FIGS. 38-48, an alternative lock-and-releasecompression insert 214 is illustrated for use with the shank 4, receiver10, retainer 12, closure top 18 and rod 21 previously described herein,the resulting assembly identified as an assembly 201 in FIGS. 47 and 48,for example. The insert 214 is substantially similar to the insert 14previously described herein, with addition features that includepositioning and locking apertures and bores and an outer cylindricalsurface 374 that is sized for a locking interference fit with thecylindrical surface 90 of the receiver 10 as will be described ingreater detail below.

Thus, the locking insert 214 includes a cylindrical body 356, opposedarms 357, a through bore 360, a U-shaped channel 361, a channel seat362, outer upper arm surfaces 363, top arm surfaces 364, an innercylindrical surface 366, an inner spherical surface 368, a base surface369, an inner gripping portion 370, outer v-shaped grooves 375A and375B, recessed areas 378, opposed bevels or flats 379 and a surface 380partially defining the recessed area 378 that are the same orsubstantially similar in form and function to the respective cylindricalbody 156, opposed arms 157, through bore 160, U-shaped channel 161,channel seat 162, outer upper arm surfaces 163, top arm surfaces 164,inner cylindrical surface 166, inner spherical surface 168, base surface169, inner gripping portion 170, grooves 175A and 175B, recessed areas178, opposed bevels or flats 179 and surfaces 180 partially definingeach of the recessed areas 178 previously described herein with respectto the insert 14.

Furthermore, the insert 214 includes a lower arm surface 374 that issimilar to the arm surface 174 of the insert 14 with the exception thatthe cylindrical surface 374 is sized for a locking interference fit withthe receiver cylindrical surface 90. In other words, a diameter of thesurface 374 is sized large enough to require that the cylindricalsurface 374 must be forced into the cylindrical surface 90 by a tool ortools or by the closure top 18 forcing the rod 21 downwardly against theinsert 214 with sufficient force to interferingly lock the insert intothe receiver surface 90.

In addition to the grooves 375A and 375B, the insert 214 upper armsurfaces 363 include a through hole or bore 376 for receiving tooling,such as that shown in FIGS. 51 and 58, for example. Formed in eachsurface 363 as well as in a portion of each outer surface 374 is av-notch or recess formed from an upper sloping surface 377 and a lowerplanar surface 377′. The through holes 376 and surfaces 377 and 377′cooperate and align with the receiver aperture surfaces 75, 77 and 75′when receiving tooling as will be described in greater detail below.

With reference to FIGS. 45-48, the insert 214 is assembled with thereceiver 10, retainer 12, shank 4, rod 21 and closure top 18 in a mannerthe same as previously described above with respect to the assembly 1,with the exception that the insert 214 must be forced downwardly into alocking interference fit with the receiver 10 when the shank 4 is lockedin place, as compared to the easily sliding relationship between theinsert 14 and the receiver 10. In particular, with reference to FIG. 45,prior to assembly with the rod 21 and the closure top 18, thecompression insert 214 outer arm surfaces 374 are slidingly received byreceiver surfaces 88, but are not received by the surfaces 90. Theinsert 214 is thus prohibited from moving any further downwardly at thebeginning of the surface 90 unless forced downwardly by a locking toolor by the closure top pressing downwardly on the rod that in turnpresses downwardly on the insert 214 as shown in FIGS. 47 and 48. Withfurther reference to FIG. 47, at this time, the receiver 10 may bearticulated to a desired angular position with respect to the shank 4,such as that shown in FIG. 54, for example, that will be held, but notlocked, by the frictional engagement between the retainer 12 and theshank upper portion 8.

The rod 21 is eventually positioned in an open or percutaneous manner incooperation with the at least two bone screw assemblies 1. The closurestructure 18 is then inserted into and advanced between the arms 62 ofeach of the receivers 10. The closure structure 18 is rotated, using atool engaged with the inner drive 186 until a selected pressure isreached at which point the rod 21 engages the U-shaped seating surface362 of the compression insert 214, further pressing the insert sphericalsurface 368 and stepped shank gripping surfaces 370 against the shankspherical surface 34, the edges of the stepped surfaces 370 penetratinginto the spherical surface 34, pressing the shank upper portion 8 intolocked frictional engagement with the retainer 12. Specifically, as theclosure structure 18 rotates and moves downwardly into the respectivereceiver 10, the point 189 and rim 190 engage and penetrate the rodsurface 22, the closure structure 18 pressing downwardly against andbiasing the rod 21 into compressive engagement with the insert 214 thaturges the shank upper portion 8 toward the retainer 12 and into lockingengagement therewith, the retainer 12 frictionally abutting the surface104 and expanding outwardly against the cylindrical surface 101. Forexample, about 80 to about 120 inch pounds of torque on the closure topmay be applied for fixing the bone screw shank 6 with respect to thereceiver 10. Tightening the helical flange form to 100 inch pounds cancreate 1000 pounds of force and it has been found that an interferencefit is created between the cylindrical portions 374 of the insert 214and the cylindrical portions 90 of the receiver at between about 700-900inch pounds. So, as the closure structure 18 and the rod 21 press theinsert 14 downwardly toward the base of the receiver 10, the insertcylindrical surface 374 is forced into the receiver cylindrical surface90, thus forcing and fixing the insert 14 into frictional interferenceengagement with the receiver surface 90.

With reference to FIG. 49, at this time, the closure top 18 may beloosened or removed and/or the rod 21 may be adjusted and/or removed andthe frictional engagement between the insert 214 and the receiver 10 atthe receiver surface 90 will remain locked in place, advantageouslymaintaining a locked angular position of the shank 4 with respect to thereceiver 10.

With further reference to FIGS. 49 and 50, at this time, another rod,such as the deformable rod 221 and cooperating alternative closure top218 may be loaded onto the already locked-up assembly to result in analternative assembly 201′. As mentioned above, the closure drive 286 mayadvantageously be made smaller than the drive of the closure 18, suchthat the deformable rod 221 is not unduly pressed or deformed duringassembly since the polyaxial mechanism is already locked.

With reference to FIGS. 51-53, a two-piece tool 600 is illustrated forreleasing the insert 214 from the receiver 10. The tool 600 includes aninner flexible tube-like structure with opposed inwardly facing prongs612 located on either side of a through-channel 616. The channel 616 mayterminate at a location spaced from the prongs 612 or may extend furtherupwardly through the tool, resulting in a two-piece tool 610. The tool600 includes an outer, more rigid tubular member 620 having a smallerthrough channel 622. The member 620 slidingly fits over the tube 610after the flexible member 610 prongs 612 are flexed outwardly and thenfitted over the receiver 10 and then within through bores of the opposedapertures 74 of the receiver 10 and aligned opposed bores 376 located onarms of the insert 214. In FIG. 51, the tool 600 is shown during theprocess of unlocking the insert 214 from the receiver 10 with the outermember 620 surrounding the inner member 610 and holding the prongs 612within the receiver and insert apertures while the tool 600 is pulledupwardly away from the shank 4. It is foreseen that the tool 600 mayfurther include structure for pressing down upon the receiver 10 whilethe prongs and tubular member are pulled upwardly, such structure may belocated within the tool 600 and press down upon the top surfaces 73 ofthe receiver arms, for example.

Alternatively, another manipulation tool (not shown) may be used that isinserted into the receiver at the opening 66 and into the insert channel361, with prongs or extensions thereof extending outwardly into theinsert through bores 376; a piston-like portion of the tool thereafterpushing directly on the shank upper portion 8, thereby pulling theinsert 214 surface 374 away from the receiver surface 90 and thusreleasing the polyaxial mechanism. At such time, the shank 4 may bearticulated with respect to the receiver 10, and the desired frictionfit returns between the retainer 12 and the shank surface 34, so that anadjustable, but non-floppy relationship still exists between the shank 4and the receiver 10. If further disassembly if the assembly is desired,such is accomplished in reverse order to the procedure describedpreviously herein for the assembly 1.

With reference to FIGS. 54-56, another manipulation tool, generally 700is illustrated for independently locking the insert 214 to the receiver10. The tool 700 includes a pair of opposed arms 712, each having anengagement extension 716 positioned at an angle with respect to therespective arm 712 such that when the tool is moved downwardly towardthe receiver, one or more inner surfaces 718 of the engagement extension716 slide along the surfaces 77 of the receiver and 377 of the insert214 to engage the insert 214, with a surface 720 pressing downwardly onthe insert surfaces 377′, pushing the cylindrical surfaces 374 into aninterference locking fit within the receiver surfaces 90. As shown inFIG. 56, when the insert 214 is locked against the receiver 10, the toolbottom surfaces 720 do not bottom out on the receiver surfaces 75′, butremained spaced therefrom. In the illustrated embodiment, the surface718 is slightly rounded and each arm extension 716 further includes aplanar lower surface 722 that creates an edge with the bottom surface720 for insertion and gripping of the insert 214 at the juncture of thesurface 377 and the surface 377′. The tool 700 may include a variety ofholding and pushing/pulling mechanisms, such as a pistol grip tool, thatmay include a ratchet feature, a hinged tool, or, a rotatably threadeddevice, for example.

With reference to FIGS. 57 and 58, another alternative non-lockinginsert 414 according to the invention is shown. The insert 414 may beused in lieu of either the insert 14 or the insert 214 with the shank 4,receiver 10, retainer 12, rod 21 and closure top 18 previously describedherein. The insert 414 is assembled with the shank 4, receiver 10,retainer 12, rod 21 and closure top 18 as previously discussed withrespect to the assembly 1. In FIG. 58, the resulting assembly thatincludes the insert 414 is identified as an assembly 401.

The insert 414 is identical to the insert 214 with two exceptions: theinsert 414 does not include the tool receiving holes or through bores376 of the insert 214 and the insert 414 has a lower outer arm surface574 that is similar in form to the surface 374 of the insert 214, but issized smaller for a sliding, non-locking fit within the receivercylindrical surface 90. The insert 414 does however include a v-notch orsloping aperture with a sloping surface 577 and a planar base surface577′ that is the same or substantially similar to the aperture with therespective sloping surface 377 and base surface 377′ of the insert 214.All other features of the insert 414 are identical or substantiallysimilar to the insert 214.

With reference to FIG. 58, the assembly 401 that includes the insert 414is shown with the locking tool 700 previously described herein. Thelocking tool 700 presses against the surfaces 577 and 577′ of thev-notches of the insert 414 to place a temporary, locking force on theshank head 8 that temporarily locks the shank 4 into position withrespect to the receiver 10, allowing a surgeon to manipulate theassembly 401 as if it were a mono-axial or fixed screw as long as thetool 700 presses inwardly and downwardly on the receiver 10 and theinsert 414. However, also advantageously, when the surgeon no longerrequires such rigid and fixed connection between the shank 4 and thereceiver 10, the tool 700 may be removed and a non-floppy, but movablefriction fit relationship returns between the shank 4 and the receiver10 due to the frictional engagement of the retainer 12 flex tabs orfingers and the shank head 8 surface 34.

With reference to FIGS. 59-92 the reference number 1001 generallyrepresents another alternative polyaxial bone screw apparatus orassembly according to the present invention. The assembly 1001 includesa shank 1004, that further includes a body 1006 integral with anupwardly extending upper portion or head structure 1008; a receiver1010; a friction fit retainer 1012, and a compression or pressure insert1014. The receiver 1010, retainer 1012 and compression insert 1014 areinitially assembled and may be further assembled with the shank 1004either prior or subsequent to implantation of the shank body 1006 into avertebra 1017 (see FIG. 85), as will be described in greater detailbelow. FIGS. 59 and 89-92 further show a closure structure 1018 forcapturing a longitudinal connecting member, for example, a rod 1021which in turn engages the compression insert 1014 that presses againstthe shank upper portion 1008 into fixed frictional contact with theretainer 1012, so as to capture, and fix the longitudinal connectingmember 1021 within the receiver 1010 and thus fix the member 1021relative to the vertebra 1017. The illustrated rod 1021 is identical orsubstantially similar to the rod 21 previously described herein. Likethe assembly 1 previously described herein, the receiver 1010 and theshank 1004 cooperate in such a manner that the receiver 1010 and theshank 1004 can be secured at any of a plurality of angles, articulationsor rotational alignments relative to one another and within a selectedrange of angles both from side to side and from front to rear, to enableflexible or articulated engagement of the receiver 1010 with the shank1004 until both are locked or fixed relative to each other near the endof an implantation procedure.

The shank 1004, best illustrated in FIGS. 59-61, is identical orsubstantially the same in form and function as the shank 4 previouslydescribed herein with respect to the assembly 1. Thus, the shank 1004includes the shank body 1006, the head or upper portion 1008, a thread1024 on the body 1006, a neck 1026, a bottom tip 1028, a shank top 1032where the thread 1024 begins, a shank head spherical surface 1034, a toprim surface 1038, a frusto-conical surface 1039, a counter sunk base1045 partially defining an internal drive feature or imprint 1046 and asmall central cannulation bore 1050 that are the same or substantiallysimilar to the respective the shank body 6, head or upper portion 8,thread 24, neck 26, tip 28, shank top 32, shank head spherical surface34, top rim surface 38, frusto-conical surface 39, counter sunk base 45,internal drive feature 46 and cannulation bore 50 of the shank 4 of theassembly 1 previously described herein.

With particular reference to FIGS. 59 and 62-67, the receiver 1010 issubstantially similar to the receiver 10 previously described herein,particularly with respect to inner surfaces that cooperate with theretainer 1012 that is substantially similar to the retainer 12, butthere are some differences due to the fact that the receiver 1010cooperates with the insert 1014 that is not a drop and rotate insertlike the insert 14 of the assembly 1. Rather, the receiver 1010 includessurface features for receiving the retainer 1012 surfaces that extendthrough an upper channel of the receiver 1010 as will be described ingreater detail below. The receiver 1010 has a generally U-shapedappearance with a partially discontinuous, partially faceted andpartially curved outer profile and partially cylindrical inner and outerprofiles. The receiver 1010 has an axis of rotation B that is shown inFIG. 59 as being aligned with and the same as an axis of rotation A ofthe shank 1004, such orientation being desirable, but not requiredduring assembly of the receiver 1010 with the shank 1004. After thereceiver 1010 is pivotally attached to the shank 1004, either before orafter the shank 1004 is implanted in a vertebra 1017, the axis B istypically disposed at an angle with respect to the axis A, as shown, forexample, in FIG. 104 with respect to the assembly 1001′ that alsoincludes the shank 1004 and the receiver 1010.

The receiver 1010 includes a curvate lower base portion 1060 defining abore or inner cavity, generally 1061, the base 1060 being integral witha pair of opposed upstanding arms 1062 forming a cradle and defining achannel 1064 between the arms 1062 with an upper opening, generally1066, and a substantially planar lower channel portion or seat 1068, thechannel 1064 having a width for operably receiving the rod 1021 orportion of another longitudinal connector between the arms 1062, as wellas closely receiving laterally extending portions of the insert 1014,the channel 1064 communicating with the base cavity 1061. Inner opposedsubstantially planar perimeter arm surfaces 1069 partially define thechannel 1064 and are located on either side of each arm interior surfacegenerally 1070. Lower opposed substantially planar and parallel surfaceportions 1071 of the arm surfaces 1069 terminate at the lowersubstantially planar seat 1068. The arm interior surfaces 1070, eachinclude various inner cylindrical profiles, an upper one of which is apartial helically wound guide and advancement structure 1072 locatedadjacent top surfaces 1073 of each of the arms 1062. In the illustratedembodiment, the guide and advancement structure 1072 is a partialhelically wound interlocking flangeform configured to mate underrotation with a similar structure on the closure structure 1018.However, it is foreseen that for certain embodiments of the invention,the guide and advancement structure 1072 could alternatively be asquare-shaped thread, a buttress thread, a reverse angle thread or otherthread-like or non-thread-like helically wound discontinuous advancementstructures, for operably guiding under rotation and advancing theclosure structure 1018 downward between the arms 1062, as well aseventual torquing when the closure structure 1018 abuts against the rod1021 or other longitudinal connecting member. It is foreseen that thearms 1062 could have break-off extensions.

An opposed pair of upper rounded off triangular or delta-shaped toolreceiving and engaging apertures 1074, each having a through bore formedby an upper arched surface 1075 and a substantially planar bottomsurface 1075′, are formed on outer surfaces 1076 of the arms 1062. Eachthrough bore surface 1075 and 1075′ extends through the arm innersurface 1070. The apertures 1074 with through bore portions 1075 and1075′ are sized and shaped for receiving portions of the retainer 1012during top loading of the retainer from the receiver opening 1066 andinto the base cavity 1061 as shown, for example, in FIG. 80. Eachaperture 1074 further includes a sloping tool alignment surface 1077that surrounds the arched bore portion 1075 and does not extendcompletely through the respective arm 1062. The sloping surface 1077allows for an angled or sloping tool receiving interface runningobliquely with respect to the receiver axis B. It is noted that thereceiver 1010 is an integral structure and devoid of any spring tabs orcollet-like structures. As will be discussed in greater detail below,the geometry of the insert 1014 that extends outwardly into the receiverchannel 1065 at the perimeter arms surfaces 1069 prohibit the insert1014 from rotating during assembly and thus misalignments with thereceiver 1010 and the rod 1021 or other longitudinal connecting memberthat sometimes occurs with compression inserts does not occur in theassembly shown in FIG. 59. Two additional rectangular shaped throughbores 1078 are also formed in the arms 1062 and are located directlybelow the apertures 1074. It is foreseen that the opening 1078 couldassume almost any shape. The through bores 1078 are sized and shaped forreceiving spring tab portions of the retainer 1012 during final assemblyand operation, the bores 1078 capturing and retaining the retainer 1012within the receiver as shown, for example, in FIG. 88. An upper surface1079 defining each bore 1078 functions as an upper stop for a portion ofthe retainer 1012. Some or all of the apertures 1074 and 1078 andadditional tool receiving apertures or grooves (not shown) may be usedfor holding the receiver 1010 during assembly with the insert 1014, theretainer 1012 and the shank 1004; during the implantation of the shankbody 1006 into a vertebra when the shank is pre-assembled with thereceiver 10; during assembly of the bone anchor assembly 1001 with therod 1021 and the closure structure 1018; and during lock and releaseadjustment of some inserts according to the invention with respect tothe receiver 1010, either into or out of frictional engagement with theinner surfaces of the receiver 1010 as will be described in greaterdetail below. It is foreseen that tool receiving grooves or aperturesmay be configured in a variety of shapes and sizes and be disposed atother locations on the receiver arms 1062.

Returning to the interior surface 1070 of the receiver arms 1062,located below the guide and advancement structure 1072 is adiscontinuous cylindrical surface 1082 partially defining a run-outfeature for the guide and advancement structure 1072. The cylindricalsurface 1082 has a diameter equal to or slightly greater than a greaterdiameter of the guide and advancement structure 1072. Moving downwardly,in a direction toward the base 1060, following the cylindrical surface1082 of each arm is a cylindrical surface (or, in some embodiments, atapered surface) 1088 located below an annular run-out seat or surface1085 that extends inwardly toward the axis B and runs perpendicular orsomewhat obliquely towards the axis B. The surface 1088 has a diametersmaller than the diameter of the surface 1082. The surface 1088 is sizedand shaped to initially closely receive a portion of the insert 1014. Adiscontinuous annular surface or narrow ledge 1089 is located below thesurface 1088 and is substantially perpendicular to the axis B. Apartially discontinuous cylindrical surface 1090 is located on each armbelow and adjacent to the surface 1089. The surface 1090 has a diameterslightly smaller than the diameter of the surface 1088. It is noted thatin some embodiments of the invention, the surfaces 1088 and 1090 arecombined and form a single cylindrical surface.

The through bores 1075 of the apertures 1074 each extend through thearms at the surfaces 1082, 1088 and 1090 with the sloping toolengagement walls 1077 extending substantially on either side of eachbore surface 1075 and formed in the arm outer surfaces 1076 at alocation primarily opposite the inner surface 1088.

With particular reference to FIGS. 59, 63 and 64, returning to thesubstantially planar peripheral surfaces 1069, each arm 1062 includes apair of projecting ridges or stops 1092, located on each surface 1069,for a total of four stops 1092 that are located near the annular surface1085 and extend from front and back arm surfaces or faces 1094 to thecylindrical surface 1088. The stops 1092 of one arm 1062 directly facethe opposing pair of stops 1092 on the other arm 1062, each stop 1092projecting outwardly from the respective planar surface 1069. Theillustrated stops 1092 are elongate and run in a direction perpendicularto the axis B. As will be described in greater detail below, the stops1092 cooperate with surfaces of the insert 1014 to retain the insert1014 within the channel 1064 of the receiver 1010. In the illustratedembodiment, each stop 1092 includes a bottom surface or ledge 1095adjacent to a partially planar and partially curved surface 1096. Aplanar portion of the surface 1096 located directly beneath the stop1092 is in line with or may be slightly inset from the surface 1069.Each set of opposed surfaces 1096 curve toward one another and terminateat the respective adjacent lower surface portions 1071. An edge 1097defines a juncture of each curved surface 1096 and the respectiveadjacent lower surface portion 1071. A first width measured betweenopposing surface portions 1071 is smaller than a second width measuredbetween opposed surfaces 1069 located between the stops 1092 and arm topsurfaces 1073, providing opposed planar locking interference fitsurfaces for the insert 1014′ as will be described in greater detailbelow. The insert 1014 is sized and shaped to be closely received butslidable between the surfaces 1071.

Returning to FIGS. 66 and 67, an annular surface 1098 partially definesthe base cavity 1061 and is located below and adjacent to thecylindrical surface 1090. The surface 1098 is disposed substantiallyperpendicular to the axis B, but could be oblique. Another cylindricalsurface 1099 is located below and adjacent to the surface 1098. Thesurface 1099 also defines an upper cylindrical surface of the basecavity 1061. The cylindrical surface 1099 is oriented substantiallyparallel to the axis B and is sized and shaped to receive an expandedportion of the retainer 1012. The surfaces 1098 and 1099 define acircumferential recess that is sized and shaped to receive the retainer1012 as it expands around the shank upper portion 1008 as the shank 1008moves upwardly through the receiver base and toward the channel 1064during assembly. It is foreseen that the recess could be tapered orconical in configuration. A cylindrical surface 1101 located below thecylindrical surface 1099 is sized and shaped to closely receive andsurround a lower portion of the retainer 1012 when the retainer is in asubstantially neutral position as shown in FIG. 88, for example. Thus,the cylindrical surface 1101 has a diameter smaller than the diameter ofthe cylindrical surface 1099 that defines the expansion area orexpansion chamber for the retainer 1012. The surface 1101 is joined orconnected to the surface 1099 by one or more beveled, curved or conicalsurfaces 1102. The surfaces 1102 allow for sliding and neutral ornominal positioning of the retainer 1012 into the space defined by thesurface 1101 and ultimate seating of the retainer 1012 on a lowersubstantially horizontal annular surface 1104 located below and adjacentto the cylindrical surface 1101.

Located below and adjacent to the annular seating surface 1104 isanother substantially cylindrical surface 1106 that communicates with abeveled or flared bottom opening surface 1107, the surface 1107communicating with an exterior base surface 1108 of the base 1060,defining a lower opening, generally 1110, into the base cavity 1061 ofthe receiver 1010.

With particular reference to FIGS. 59 and 68-73, the lower open or splitfriction fit retainer 1012, that operates to capture the shank upperportion 1008 within the receiver 1010, has a central axis that isoperationally the same as the axis B associated with the receiver 1010when the shank upper portion 1008 and the retainer 1012 are installedwithin the receiver 1010. The retainer 1012 includes a substantiallycylindrical discontinuous lower body 1116, a plurality of flex fingersor panels, 1117 extending upwardly from the body 1116 and a pair ofopposed spring arms or tabs 1118, also extending upwardly from the body1116. The retainer ring 12 is made from a resilient material, such as astainless steel or titanium alloy, so that the retainer 1012 body 1116may be expanded and the fingers and tabs (1117 and 1118) of the retainermay be manipulated during various steps of assembly as will be describedin greater detail below. The retainer 1012 has a central channel orhollow through bore, generally 1121, that passes entirely through theretainer 1012 from tab 1118 top surfaces 1122 to a bottom surface 1124of the retainer body 1116. Surfaces that define the channel or bore 1121at the body 1116 include an inner lower frusto-conical surface 1128adjacent to the retainer body bottom surface 1124, a substantiallycylindrical surface 1130 adjacent the frusto-conical surface 128 and apartially continuous partially discontinuous substantially radiused orspherical surface 1132 located adjacent the cylindrical surface 1130,the surface 1132 being substantially continuous near the surface 1130and at each of the spring tabs 1118 and otherwise broken by a throughslot or slit, generally 1134 and a plurality of evenly spaced partialslots or grooves 1136. The grooves 1136 separate the surface 1132 into aplurality of segments or pieces that have already been described hereinas the flex fingers 1117. The grooves or slots 1136 run outwardly andupwardly from the retainer body 1116 through an upper surface 1137 ofthe retainer 1012 located between the spring tabs 1118. In theillustrated embodiment, the slots 1136 and the through slit 1134 formthe six substantially uniform flex fingers or tabs 1117 as well aspartially define the two spring tabs 1118, each finger 1117 having theinner spherical surface 1132 while each of the spring tabs 1118 extendoutwardly and away from the surface 1132 at the retainer body 1116. Itis foreseen that more or fewer flex fingers may be made by the formingof more or fewer slots 1136 and that the surface 1132 could be planar,tapered, faceted or otherwise curved. The illustrated discontinuousspherical surface 1132 is sized and shaped to closely fit about and snaponto the shank surface 1034 during assembly as will be described ingreater detail below. Preferably the surface 1132 has a radius the same,slightly smaller or slightly larger than the radius of the sphericalshank surface 1034. The surface 1132 could be bent or deformed inwardlyor outwardly to better cooperate with the shank head. In operation, thediscontinuous surface 1132 advantageously frictionally engages the bonescrew shank upper portion or head 1008, allowing for an un-lockedfriction fit, non-floppy placement of the angle of the shank 1004 withrespect to the receiver 1010 during surgery prior to locking of theshank 1004 with respect to the receiver 1010 near the end of theprocedure. At the time of locking engagement, as shown in FIG. 95, forexample, downward and outward force placed on the retainer 1012 by theshank upper portion 1008 expands the retainer body 1116 at the slit 1134and the individual flex fingers 1117 no longer frictionally grip thespherical head surface 1034 of the upper portion 1008. To aid in bendingflexibility and resiliency, some or all of the flex fingers 1117 mayhave sloping outer surfaces or other geometry to gain the level ofresiliency desired for expansion and gripping of the fingers 1117 aboutthe shank upper portion 1008. For example, the illustrated fingers 1117each include an outer bevel 1138. The spherical surfaces 1132 mayinclude a surface treatment or roughening to provide a desired frictionfit. Again, it is noted that the surfaces 1132 need not be spherical andmay be planar or include other surface geometries that resiliently gripthe shank upper portion or head 1008. Again, in some embodiments, theflexible tabs 1117 may be bent or deformed to further enhance frictionalengagement. It is noted that the fingers 1117 that are directedgenerally upwardly toward the receiver channel 1064 advantageouslysufficiently snap about and then grip the shank surface 1034 to anextent to provide the friction fit desired for non-floppy placement ofthe shank body 1006 at a desired angle with respect to the receiver 1010during manipulation of the bone screws 1001 and the rod 1021 or otherlongitudinal connecting member during surgery. However, as compared tobone screw inserts such as collets known in the art that includedownwardly directed portions or panels that are ultimately wedgedbetween a receiver surface and a shank surface upon final locking of theshank to the receiver, the thin upwardly directed fingers 1117 thatextend away from the shank locking surface that are not as strong as theretainer body 1116 or the insert 1114, do not participate or cooperatewith the final locking of the insert 1114 to the shank upper portion1008, the shank upper portion 8 to the retainer 1012, and the retainer1012 to the receiver inner and substantially planar surfaces 1101 and1104. For such purpose, the more substantial retainer body 1116 locatedbelow the slots 1136 having only the very narrow slit 1134, used forexpansion purposes only, is the component or portion that locks theshank upper portion 1008 between the receiver 1010, the insert 1114 andthe rod 1021 or other longitudinal connecting member.

The retainer body 1116 and the flex fingers 1117 have an outersubstantially cylindrical profile, sized and shaped to closely andslidingly fit within the receiver cavity 1061. Opposed flex fingers 1117located centrally between the spring tabs 1118, each include a smallgroove 1140 sized and shaped to receive a portion of the insert 1014 aswill be described in greater detail below.

The opposed pair of spring tabs 1118, extend outwardly away from oneanother and thus outwardly from the body 1116. Each spring tab 1118 issized and shaped to closely cooperate and frictionally engage uppersurfaces 1079 defining the receiver through bores 1078. An outer surface1143 of each spring tab 1118 located adjacent each upper surface 1122 issized and shaped to cooperate with and frictionally engage thecylindrical surface 1090 during assembly and shipping as shown, forexample, in FIG. 83. In some embodiments of the invention, the tab 1118surface 1143 may include one or more projections, grooves or notches asneeded for tooling to resiliently hold the retainer in an upper portionof the cavity 1061 when desired, but readily release the retainer 1012into a lower portion of the receiver cavity 1061 once the retainer flextabs 1117 engage the shank head 1008. The illustrated spring tabs 1118each include one or more planar or curved concave inner surfaces 1144running from the top surface 1122 to a tab base seat, surface orsurfaces 1145 located adjacent to and running laterally outwardly fromthe surface 1132. The surfaces 1144 extend both outwardly and upwardlyfrom the base seat surfaces 1145. It is foreseen that in otherembodiments of the invention, fewer or greater number of planar or othersurfaces with other geometries may extend between the top surface 1122and the inner surfaces defining the body 1116 of the retainer 1012.

The through slit 1134 of the resilient retainer 1012 is defined by firstand second end surfaces, 1146 and 1147 disposed in spaced relation toone another (they may also be touching) when the retainer is in aneutral state. Both end surfaces 1146 and 1147 are disposedsubstantially perpendicular to the bottom surface 1124. A width Xbetween the surfaces 1146 and 1147 is very narrow (slit may be made byEDM process) to provide stability to the retainer 1012 during operation.Because the retainer 1012 is top loadable in a neutral state and theretainer 1012 does not need to be compressed to fit within the receivercavity 1061, the width X may be much smaller than might be required fora bottom loaded compressible retainer ring. The gap X functions only inexpansion to allow the retainer 1012 to expand about the shank upperportion 1008. This results in a stronger retainer that provides moresurface contact with the shank upper portion 1008 upon locking,resulting in a sturdier connection with less likelihood of failure thana retainer ring having a greater gap. Furthermore, because the retainer1012 body 1116 is only expanded and never compressed inwardly, theretainer 1012 does not undergo the mechanical stress that typically isplaced on spring ring type retainers known in the prior art that areboth compressed inwardly and expanded outwardly during assembly.

It is foreseen that in some embodiments of the invention, the retainer1012 inner surfaces may include a roughening or additional material toincrease the friction fit against the shank upper portion 1008 prior tolock down by the rod 1021 or other longitudinal connecting member. Also,the embodiment shown in FIGS. 68-73 illustrates the surfaces 1146 and1147 as substantially parallel to the central axis of the retainer,however, it is foreseen that it may be desirable to orient the surfacesobliquely or at a slight angle.

With particular reference to FIGS. 59 and 74-79, the compression insert1014 is illustrated that is sized and shaped to be received by anddown-loaded into the receiver 1010 at the upper opening 1066. Thecompression insert 1014 has an operational central axis that is the sameas the central axis B of the receiver 1010. In operation, the insertadvantageously frictionally engages the bone screw shank upper portion1008. As will be described in greater detail below with respect to theinsert 1014′ illustrated in FIGS. 93-95, in some embodiments of theinvention, the insert that has locked the shank 1004 in a desiredangular position with respect to the receiver 1010, by, for example,compression from the rod 1021 and closure top 1018, is also forced intoan interference fit engagement with the receiver 1010 at the pair ofopposed planar arm surfaces 1071 thereof and thus is capable ofretaining the shank 1006 in a locked position even if the rod 1021 andclosure top 1018 are removed. Such locked position may also be releasedby the surgeon if desired. The non-locking insert 1014 as well as thelocking insert 1014′ are preferably made from a solid resilientmaterial, such as a stainless steel or titanium alloy, so that portionsof the insert may be pinched or pressed. against and un-wedged from thereceiver 1010 with a release tool.

The non-locking compression insert 1014 includes a substantiallyU-shaped body 1150 having opposed ends, generally 1151, the body 1150being sized and shaped to extend completely through the U-shaped channel1064 between the opposed front and back surfaces or faces 1094 of thearms 1062 so as to cooperate with the receiver arm side surfaces 1069,the stops 1092, the surfaces 1096 and 1071 below the stops 1092 and thechannel seat 1068. A U-shaped channel surface or saddle 1153 formed inthe body 1150 also extends between the insert ends 1151 and when theinsert 1014 is assembled with the receiver 1010, the saddle 1153substantially aligns with the receiver channel 1064. The saddle 1153 isformed by the insert body 1150 and by two upstanding arms 1157 and issized and shaped to closely receive the rod 1021 or other longitudinalconnecting member. It is foreseen that an alternative insert embodimentmay be configured to include planar holding surfaces that closely hold asquare or rectangular bar as well as hold a cylindrical rod-shaped,cord, or sleeved cord longitudinal connecting member. A bore, generally1160, is disposed primarily within and through the insert body 1150 thatruns along the axis B and communicates with the U-shaped channel formedby the saddle 1153 and upstanding arms 1157. The bore 1160 is sized andshaped to provide space and clearance for shank driving and othermanipulation tools.

The arms 1157 that are disposed on either side of the saddle 1153 extendupwardly therefrom and are sized and configured for ultimate placementabove the retainer spring tabs 1118 and beneath and spaced from theclosure top 1118 within the cylindrical run-out surface 1082 locatedbelow the receiver guide and advancement structure 1072. The arms 1157include outer curved, convex surfaces 1163 that are illustrated aspartially cylindrical, and planar top surfaces 1164 that are ultimatelypositioned in spaced relation with the closure top 1018, so that theclosure top 1018 frictionally engages the rod 1021 only, pressing therod 1021 downwardly against the insert saddle 1153, the shank 1004 upperportion 1008 then pressing against the retainer 1012 to lock thepolyaxial mechanism of the bone screw assembly 1001 at a desired angle.The partially cylindrical surface 1163 extends from each top surface1164 to a substantially annular bottom surface 1165 of the insert 1014.The surface 1163 is sized and shaped to generally fit within thereceiver arms 1062 and also within the opposed retainer spring tab innersurfaces 1144. It is foreseen that in some embodiments of the invention,the arms 1157 may be extended and the closure top configured such thatthe arms and, more specifically, the surfaces 1164 ultimately directlyengage the closure top 1018 for locking of the polyaxial mechanism, forexample, when the rod 1021 is made from a deformable material. The armouter surfaces 1163 further include notches or grooves formed thereonfor receiving manipulation, unlocking and locking tools. In theillustrated embodiments, each surface 1163 includes a through bore orhole 1166 for receiving tooling, such as that shown in FIG. 101, forexample. Located below the through bore 1166 and formed in each surface1163 is a v-notch or recess for receiving tooling, such as that shown inFIGS. 104 and 106, the notch defined by an upper sloping surface 1167adjacent to the through bore 1166 and intersecting a lower planarsurface 1168 disposed substantially perpendicular to a central axis ofthe insert 1014. Each through hole 1166, surfaces 1167 and surface 1168cooperate and align with the respective receiver aperture through bore1075, surface, and surface 1075′ when the insert 1014 is captured andoperationally positioned within the receiver 1010 as will be describedin greater detail below. The insert outer arm surfaces 1163 are sizedand shaped to be slidingly received by the surfaces 1144 of the retainerspring tabs 1118 during assembly and are spaced from the spring tabs1118 after final locking of the assembly 1001.

The insert 1014 extends from the substantially cylindrical outer armssurfaces 1163 equally outwardly to each end 1151. Substantially planarouter side surfaces 1170 extend from each arm surface 1163 to asubstantially planar surface 1171 disposed perpendicular thereto, thesurfaces 1171 substantially defining each of the ends 1151. Each endsurface 1171 is adjacent to a lower or base extension surface 1172 thatruns parallel to the base surface 1165 and extends inwardly toward theinsert body 1150. Adjacent to each side surface 1170 is a substantiallyplanar upper or top surface 1173 running from one of the arms 1157 toeach of the end surfaces 1171. Each of the surfaces 1170 form a narrowouter strip and are adjacent and perpendicular to a lower narrow ledge1174. The ledges 1174 run parallel to the upper surfaces 1173. An insetplanar surface 1175 is adjacent to each lower ledge surface 1174 andruns parallel to the respective outer planar side surface 1170. A widthbetween opposing surfaces 1175 is sized such that the surfaces 1175 areslidingly received between the opposed receiver lower arm surfaces 1071.In other embodiments of the invention, a width between the surfaces 1175may be enlarged such that the surfaces 1175 must be forced downwardlybetween the planar surfaces 1071 to provide a locking interference fitof the insert against the receiver and thus lock the polyaxial mechanismof the bone screw assembly as will be described below with respect tothe insert 1014′. The surfaces 1175 terminate at the lower baseextension surface 1172. Adjacent to the surface 1172 and located oneither side of the insert body 1150 is a partial lower base body portion1176 that extends outwardly from the generally cylindrical body 1150 ofthe insert 1014, but does not extend all the way to the insert endsurfaces 1171. Each lower base body portion 1176 includes cut-outs,protrusions and tapers sized and shaped for close cooperation with theretainer 1012. For example, each base body portion 1176 is partiallydefined by a planar surface 1177 that runs parallel to the nearbysurface 1171, the surface 1177 partially defining a protrusion 1178 thatis sized and shaped to be slidingly received by and closely fit withinone of the retainer grooves 1140. The protrusion 1178 extends below theinsert substantially annular bottom surface 1165. The illustratedprotrusion is substantially rectangular in profile to match the profileof the cooperating retainer groove 1150, but in other embodiments it maybe of a different geometry to substantially match and fill the groove1140. Further cut-outs, tapers or bevels may be made to the insertsurfaces to provide adequate clearance and ease of manipulation of theinsert 1014 within the receiver 1010 and retainer 1102, such as lowersurfaces 1179 located on either side of the protrusion 1178 that areintegral and flush with the bottom surface 1165 and are sized andlocated to seat on the retainer 1012 upper planar surface 1137.

The insert bore, generally 1160, is substantially defined at the body1150 by an inner substantially cylindrical surface 1180 thatcommunicates with the saddle 1153 and also communicates with a lowerconcave substantially spherical surface 1181 having a radius the same orsubstantially similar to a radius of the surface 1034 of the shank upperportion or head 1008. The surface 1181 primarily terminates at the base1165, but also extends into and partially defines each of the lowerprotrusions 1178. Located along the spherical surface 1181 between thecylindrical surface 1180 and the annular base surface 1165 is a shankgripping surface portion 1182. The gripping surface portion 1182includes one or more stepped surfaces or ridges sized and shaped to gripand penetrate into the shank head 1008 when the insert 1014 is lockedagainst the head surface 1034. It is foreseen that the stepped surfaceportion 1182 may include grater or fewer number of stepped surfaces andcover greater or less surface area of the spherical surface 1181. It isforeseen that the shank gripping surface portion 1182 and also thespherical surface 1181 may additionally or alternatively include aroughened or textured surface or surface finish, or may be scored,knurled, or the like, for enhancing frictional engagement with the shankupper portion 1008.

The bore 1160 is sized and shaped to receive the driving tool (notshown) therethrough that engages the shank drive feature 1046 when theshank body 1006 is driven into bone with the receiver 1010 attached.Also, the bore 1160 may receive a manipulation tool used for releasingthe alternative locking insert 1014′ from a locked position with thereceiver, the tool pressing down on the shank and also gripping theinsert 1014′ at the opposed through bores 1166 or with other toolengaging features. A manipulation tool for un-wedging the insert 1014′from the receiver 1010 may also access the bores 1166 from the receiverthrough bores 1074. The illustrated insert 1014 may further includeother features, including grooves and recesses for manipulating andholding the insert 1014 within the receiver 1010 and providing adequateclearance between the retainer 1012 and the insert 1014. It is foreseenthat insert 1014 does not require bores 1166 in some embodiments.

With reference to FIGS. 59 and 89-92, the illustrated elongate rod orlongitudinal connecting member 1021 (of which only a portion has beenshown) is identical or substantially similar to the rod 21 previouslydescribed herein with respect to the assembly 1.

Longitudinal connecting members for use with the assembly 1001 may takea variety of shapes, including but not limited to rods or bars of oval,rectangular or other curved or polygonal cross-section. The shape of theinsert 1014 may be modified so as to closely hold the particularlongitudinal connecting member used in the assembly 1001. Someembodiments of the assembly 1001 may also be used with a tensioned cord.Such a cord may be made from a variety of materials, including polyesteror other plastic fibers, strands or threads, such aspolyethylene-terephthalate. Furthermore, the longitudinal connector maybe a component of a longer overall dynamic stabilization connectingmember, with cylindrical or bar-shaped portions sized and shaped forbeing received by the compression insert 1014 of the receiver having aU-shaped, rectangular- or other-shaped channel, for closely receivingthe longitudinal connecting member. The longitudinal connecting membermay be integral or otherwise fixed to a bendable or damping componentthat is sized and shaped to be located between adjacent pairs of bonescrew assemblies 1001, for example. A damping component or bumper may beattached to the longitudinal connecting member at one or both sides ofthe bone screw assembly 1001. A rod or bar (or rod or bar component) ofa longitudinal connecting member may be made of a variety of materialsranging from deformable plastics to hard metals, depending upon thedesired application. Thus, bars and rods of the invention may be made ofmaterials including, but not limited to metal and metal alloys includingbut not limited to stainless steel, titanium, titanium alloys and cobaltchrome; or other suitable materials, including plastic polymers such aspolyetheretherketone (PEEK), ultra-high-molecular weight-polyethylene(UHMWP), polyurethanes and composites, including composites containingcarbon fiber, natural or synthetic elastomers such as polyisoprene(natural rubber), and synthetic polymers, copolymers, and thermoplasticelastomers, for example, polyurethane elastomers such aspolycarbonate-urethane elastomers.

With reference to FIGS. 59 and 89-92, the closure structure or closuretop 1018 shown with the assembly 1001 is substantially similar to theclosure top 18 previously described herein with respect to the assembly1. Thus, the closure top 1018 includes an outer helically wound guideand advancement structure 1183, a top surface 1184, an internal drive1186, a base or bottom surface 1188, and a rim 1190 that aresubstantially similar in form and function to the respective guide andadvancement structure 182, top surface 184, internal drive 186, base orbottom surface 188 and rim 190 of the closure top 18 previouslydescribed herein. It is noted that in some embodiments, the closure topbottom surface 1188 may include a central point and in other embodimentsneed not include a point and/or the rim. The closure top 1018 mayfurther include a cannulation through bore (not shown) extending along acentral axis thereof and through the top and bottom surfaces thereof.Such a through bore provides a passage through the closure 1018 interiorfor a length of wire (not shown) inserted therein to provide a guide forinsertion of the closure top into the receiver arms 1062.

An alternative closure top 1218 for use with a deformable rod, such as aPEEK rod 1221, is shown in FIGS. 99 and 100. The top 1218 is identicalto the top 1018 with the exception that a point or nub 1289 is locatedon a domed surface 1290 in lieu of the rim of the closure top 1018. Theclosure top 1218 otherwise includes a guide and advancement structure1283, a top 1284, an internal drive 1286 and a bottom outer annularsurface 1288 that same or substantially similar to the guide andadvancement structure 1183, top 1184, internal drive 1186 and a bottomsurface 1188 described herein with respect to the closure top 1018. Insome embodiments, the internal drive 1286 is not as large as the drive1186 of the closure top 1018, such smaller drive providing for lessforce being placed on a deformable rod, for example, and not beingrequired when a locking insert, for example, the insert 1014′ discussedbelow is utilized in a bone screw assembly of the invention.

Returning to the assembly 1001, preferably, the receiver 1010, theretainer 1012 and the compression insert 1014 are assembled at a factorysetting that includes tooling for holding and alignment of the componentpieces and pinching or compressing of the retainer 1012 spring tabs1118, if necessary and otherwise manipulating the retainer 1012 andinsert 1014 with respect to the receiver 1010. In some circumstances,the shank 1004 is also assembled with the receiver 1010, the retainer1012 and the compression insert 1014 at the factory. In other instances,it is desirable to first implant the shank 1004, followed by addition ofthe pre-assembled receiver, retainer and compression insert at theinsertion point. In this way, the surgeon may advantageously and moreeasily implant and manipulate the shanks 1004, distract or compress thevertebrae with the shanks and work around the shank upper portions orheads without the cooperating receivers being in the way. In otherinstances, it is desirable for the surgical staff to pre-assemble ashank of a desired size and/or variety (e.g., surface treatment ofroughening the upper portion 1008 and/or hydroxyapatite on the shank1006), with the receiver, retainer and compression insert. Allowing thesurgeon to choose the appropriately sized or treated shank 1004advantageously reduces inventory requirements, thus reducing overallcost and improving logistics and distribution.

Pre-assembly of the receiver 1010, retainer 1012 and compression insert1014 is shown in FIGS. 80-84. With particular reference to FIG. 80,first the retainer 1012 is inserted into the upper receiver opening1066, leading with one of the spring tabs 1118 with both of the springtab top surfaces 1122 facing one arm 1062 and the retainer bottomsurface 1124 facing the opposing arm 1062 (shown in phantom). Theretainer 1012 is then lowered in such sideways manner into the channel1064 and partially into the receiver cavity 1061, followed by tiltingthe retainer 1012 such that the top surface 1122 of the leading springtab 1118 is moved into a nearby receiver arm aperture 1074 below thearched through bore surface 1075. With reference to FIGS. 80 and 81, theretainer 1012 is then further tilted or turned and manipulated withinthe receiver to a position within the cavity until the retainer 1012bottom surface 1124 is directed toward the receiver cavity 1061 and thespring tab upper surfaces 1122 are facing upwardly toward the receiverchannel opening 1066 as shown in FIGS. 81 and 82. To accomplish suchtilting and turning of the retainer 1012, the spring tab arm 1118located within the receiver bore surface 1075 is manipulated downwardlyand then upwardly within such bore and finally shifted out of such borewhen the opposed spring tab arm 1118 moves past and clears the guide andadvancement structure 1072 of the receiver 1010. With further referenceto FIG. 82 and also FIG. 83, the retainer 1012 is moved downwardlytoward the receiver base 1060 and the spring tabs 1118 are pressedresiliently toward one another as the retainer spring tab outsidesurfaces 1143 abut against the receiver cylindrical surfaces 1090.

Also with reference to FIGS. 82 and 83, the insert 1014 is loaded intothe receiver 1010 and may be used to push the retainer downwardly intothe desired compressed shipping position shown in FIG. 83. The insert1014 is loaded into the receiver through the opening 1066 as shown inphantom in FIG. 82 with the protrusions 1178 facing the receiver channel1064. As the insert 1014 is lowered into the receiver, the side surfaces1170 are slidingly received by the opposed receiver inner arm surfaces1069 defining the channel 1064. Once the insert 1014 protrusion 1178 andsurfaces 1179 make contact with the respective retainer groove 1140 andupper surfaces 1137 as shown in FIG. 82 with the insert lower body 1150located between the spring tabs 1118, the insert 1014 may be pressedfurther downwardly until the insert 1014 is captured within the receiver1010 as best shown in FIG. 84, with the saddle 1153 being slightlypinched or pressed to allow the opposed surfaces 1170 to engage and thenmove past the receiver stops 1092, the stops 1092 thereafter prohibitingupward movement of the insert 1014 out of the receiver channel 1064.Specifically, if the insert 1014 is moved upwardly toward the opening1066 of the receiver, the insert surfaces 1173 abut against bottomsurfaces 1095 of the stops 1092, prohibiting further upward movement ofthe insert 1014 unless a tool is used to pinch the surfaces 1170 towardone another while moving the insert 1014 upwardly toward the receiveropening 1066.

The insert 1014 and the retainer 1012 that is slightly spaced from theseating surface 1104 of the receiver 1010 and held in such position bythe spring tabs 1118 resiliently pressing against the receiver innercylindrical surfaces 1090 are now in a desired position for shipping asan assembly along with the separate shank 1004. The insert 1014protrusions 1178 are seated within the retainer grooves 1140 prohibitingfurther downward movement of the insert 1014 and the insert 1014 isfully captured within the receiver 10 by the stops 1092, prohibitingfurther upward movement thereof.

Typically, the receiver and retainer combination are shipped orotherwise provided to the end user with the spring tabs 1118 wedgedagainst the receiver as shown in FIG. 83. The receiver 1010, retainer1012 and insert 1014 combination is now pre-assembled and ready forassembly with the shank 1004 either at the factory, by surgery staffprior to implantation, or directly upon an implanted shank 1004 as willbe described herein.

As illustrated in FIG. 85, the bone screw shank 1004 or an entireassembly 1001 made up of the assembled shank 1004, receiver 1010,retainer 1012 and compression insert 1014, is screwed into a bone, suchas the vertebra 1017 (shown in phantom), by rotation of the shank 1004using a suitable driving tool (not shown) that operably drives androtates the shank body 1006 by engagement thereof at the internal drive1046. Specifically, the vertebra 1017 may be pre-drilled to minimizestressing the bone and have a guide wire (not shown) inserted therein toprovide a guide for the placement and angle of the shank 1004 withrespect to the vertebra. A further tap hole may be made using a tap withthe guide wire as a guide. Then, the bone screw shank 1004 or the entireassembly 1001 is threaded onto the guide wire utilizing the cannulationbore 1050 by first threading the wire into the opening at the bottom1028 and then out of the top opening at the drive feature 1046. Theshank 1004 is then driven into the vertebra using the wire as aplacement guide. It is foreseen that the shank and other bone screwassembly parts, the rod 1021 (also having a central lumen in someembodiments) and the closure top 1018 (also with a central bore) can beinserted in a percutaneous or minimally invasive surgical manner,utilizing guide wires and attachable tower tools mating with thereceiver. When the shank 1004 is driven into the vertebra 1017 withoutthe remainder of the assembly 1001, the shank 1004 may either be drivento a desired final location or may be driven to a location slightlyabove or proud to provide for ease in assembly with the pre-assembledreceiver, compression insert and retainer.

With further reference to FIG. 85, the pre-assembled receiver, insertand retainer are placed above the shank upper portion 1008 until theshank upper portion is received within the opening 1110. With particularreference to FIGS. 85-87A, as the shank upper portion 1008 is moved intothe interior 1061 of the receiver base, the shank upper portion 1008presses upwardly against the retainer 1012 in the recess partiallydefined by the cylindrical surface 1099. As the portion 1008 continuesto move upwardly toward the channel 6104, the surface 1034 forcesoutward movement of the retainer 1012 towards the cylindrical surface1099 defining the receiver expansion recess or chamber as shown in FIG.86. With reference to FIG. 87, the retainer 1012 begins to return to itsneutral state as the center of the sphere (shown in dotted lines) passesbeyond the center of the retainer expansion recess. At this time also,the spherical surface 1034 moves into engagement with the surfaces 1132of the retainer flex tabs 1117, the tabs 1117 expanding slightlyoutwardly to receive the surface 1034 as best shown in FIG. 87A. Withfurther reference to both FIGS. 87 and 87A, the spherical surface 1034then enters into full frictional engagement with the panel innersurfaces 1132. At this time, the retainer 1012 panels and the surface1034 are in a fairly tight friction fit, the surface 1034 beingpivotable with respect to the retainer 1012 with some force. Thus, atight, non-floppy ball and socket joint is now created between theretainer 1012 and the shank upper portion 1008.

With reference to FIG. 88, the receiver is then pulled upwardly or theshank 1004 and attached retainer 1012 are then moved downwardly into adesired position with the retainer seated on the surface 1104. Again,this may be accomplished by either an upward pull on the receiver 1010or, in some cases, by driving the shank 1004 further into the vertebra1017. At this time, the retainer spring tabs 1118 once against springoutwardly into the receiver bores 1078, making it impossible to move theretainer out of the locking portion of the chamber defined in part bythe receiver seat 1104 unless pressed inwardly by a tool or tools viathe through bores 1078. With reference to FIG. 89, the insert 1014 maybe pressed downwardly by a tool or by the rod 1021 and the closure top1018. Also, in some embodiments, when the receiver 1010 is pre-assembledwith the shank 1004, the entire assembly 1001 may be implanted at thistime by inserting the driving tool (not shown) into the receiver and theshank drive 1046 and rotating and driving the shank 1004 into a desiredlocation of the vertebra 1017.

With reference to FIGS. 88 and 89 and also, for example, to FIG. 106(that shows the use of the assembly 1001′ which is an assembly 1001 withan alternative locking insert), at this time, the receiver 1010 and maybe articulated to a desired angular position with respect to the shank1004, such as that shown in FIG. 106, that will be held, but not locked,by the frictional engagement between the retainer 1012 and the shankupper portion 1008.

With reference to FIGS. 89-92, the rod 1021 is eventually positioned inan open or percutaneous manner in cooperation with the at least two bonescrew assemblies 1001. The closure structure 1018 is then advancedbetween the arms 1062 of each of the receivers 1010. The closurestructure 1018 is rotated, using a tool engaged with the inner drive1186 until a selected pressure is reached at which point the rod 1021engages the U-shaped seating surface 1153 of the compression insert1014, pressing the insert spherical surface 1181 and stepped shankgripping surfaces 1182 against the shank spherical surface 1034, theedges of the stepped surfaces 1182 penetrating into the sphericalsurface 1034, pressing the shank upper portion 1008 into lockedfrictional engagement with the retainer 1012. Specifically, as theclosure structure 1018 rotates and moves downwardly into the respectivereceiver 1010, the rim 1190 engages and penetrates the rod surface 1022,the closure structure 1018 pressing downwardly against and biasing therod 1021 into compressive engagement with the insert 1014 that urges theshank upper portion 1008 toward the retainer 1012 inner body portion atleast partially defined by the inner surface 1130 located below thefriction fit panels 1132 and into locking engagement therewith, theretainer 1012 frictionally abutting the surface 1104 and expandingoutwardly and abutting against the cylindrical surface 1101. Forexample, about 80 to about 120 inch pounds of torque on the closure topmay be applied for fixing the bone screw shank 1006 with respect to thereceiver 1010. If disassembly if the assembly 1001 is desired, such isaccomplished in reverse order to the procedure described previouslyherein for assembly.

With reference to FIGS. 93-98, an alternative lock-and-releasecompression insert 1014′ is illustrated for use with the shank 1004,receiver 1010, retainer 1012, closure top 1018 and rod 1021 previouslydescribed herein, the resulting assembly identified as an assembly 1001′in FIGS. 97 and 98, for example. The insert 1014′ is identical orsubstantially similar to the insert 1014 previously described herein,with the exception that the insert 1014′ is sized for a lockinginterference fit with the edges 1097 and adjacent planar surfaces 1071of the receiver 1010 as will be described in greater detail below.

Thus, the locking insert 1014 includes a body 1150′, a pair of opposedends 1151′, a saddle surface 1153′, a pair of arms 1157′, a bore 1160′,outer curved arm surfaces 1163′, arm planar top surfaces 1164′, anannular bottom surface 1165′, a pair of v-shaped apertures that includearm through holes 1166′, outer sloping surfaces 1167′, and a lowerplanar surface 1168′, extended portions with outer planar side surfaces1170′, planar end surfaces 1171′, a pair of base extensions 1172′, uppersurfaces 1173′, narrow lower ledges 1174′, inset planar side surfaces1175′, lower body portions 1176′ with planar surfaces 1177′, protrusions1178′, surfaces 1179′ on either side of the protrusions, an innercylindrical surface 1180′, an inner spherical surface 1181′ and an innergripping surface portion 1182′ that are the same or substantiallysimilar in form and function to the respective body 1150, pair ofopposed ends 1151, the saddle surface 1153, arms 1157, bore 1160, outercurved arm surfaces 1163, arm planar top surfaces 1164, annular bottomsurface 1165, v-shaped apertures that include arm through holes 1166,outer sloping surfaces 1167, and a lower planar surface 1168, theextended portions with outer planar side surfaces 1170, planar endsurfaces 1171, the base extensions 1172, upper surfaces 1173, narrowlower ledges 1174, inset planar side surfaces 1175, lower body portions1176 with planar surfaces 1177, protrusions 1178, surfaces 1179 oneither side of the protrusions, and the inner cylindrical surface 1180,inner spherical surface 1181 and inner gripping surface portion 1182previously described herein with respect to the insert 1014.

The insert 1014′ planar side surfaces 1175′ are sized and shaped for alocking interference fit with the receiver at a lower portion of thereceiver channel 1064. In other words, a width measured between surfaces1175′ is sized large enough to require that the insert 1014′ must beforced into the space between the receiver surfaces 1071 starting at theedge surfaces 1097 by a tool or tools or by the closure top 1018 forcingthe rod 1021 downwardly against the insert 1014′ with sufficient forceto interferingly lock the insert into the receiver between the planarsurfaces 1071.

With reference to FIGS. 96-98, the insert 1014′ is assembled with thereceiver 1010, retainer 1012, shank 1004, rod 1021 and closure top 1018,in a manner the same as previously described above with respect to theassembly 1001, resulting in an assembly 1001′, with the exception thatthe insert 1014′ must be forced downwardly into a locking interferencefit with the receiver 1010 when the shank 1004 is locked in place, ascompared to the easily sliding relationship between the insert 1014 andthe receiver 1010. In particular, prior to assembly with the rod 1021and the closure top 1018, the compression insert 1014′ outer surfaces1170′ are slidingly received by receiver surfaces 1071, but the surfaces1175′ are not. The insert 1014′ is thus prohibited from moving anyfurther downwardly at the edges 1097 unless forced downwardly by alocking tool or by the closure top pressing downwardly on the rod thatin turn presses downwardly on the insert 1014′ as shown in FIGS. 97 and98. With further reference to FIG. 97, at this time, the receiver 1010may be articulated to a desired angular position with respect to theshank 1004, such as that shown in FIGS. 104 and 106, for example, thatwill be held, but not locked, by the frictional engagement between theretainer 1012 and the shank upper portion 1008.

The rod 1021 is eventually positioned in an open or percutaneous mannerin cooperation with the at least two bone screw assemblies 1001′. Theclosure structure 1018 is then inserted into and advanced between thearms 1062 of each of the receivers 1010. The closure structure 1018 isrotated, using a tool engaged with the inner drive 1186 until a selectedpressure is reached at which point the rod 1021 engages the U-shapedseating surface 1153′ of the compression insert 1014′, further pressingthe insert spherical surface 1181′ and stepped shank gripping surfaces1182′ against the shank spherical surface 1034, the edges of the steppedsurfaces 1182′ penetrating into the spherical surface 1034, pressing theshank upper portion 1008 into locked frictional engagement with theretainer 1012. Specifically, as the closure structure 1018 rotates andmoves downwardly into the respective receiver 1010, the rim 1190 engagesand penetrates the rod surface 1022, the closure structure 1018 pressingdownwardly against and biasing the rod 1021 into compressive engagementwith the insert 1014′ that urges the shank upper portion 1008 toward theretainer 1012 and into locking engagement therewith, the retainer 1012frictionally abutting the surface 1104 and expanding outwardly againstthe cylindrical surface 1101. For example, about 80 to about 120 inchpounds of torque on the closure top may be applied for fixing the bonescrew shank 1006 with respect to the receiver 1010. Tightening thehelical flange form to 100 inch pounds can create 1000 pounds of forceand it has been found that an interference fit is created between theplanar surfaces 1175′ of the insert 1014′ and the edges 1097 and planarsurfaces 1071 of the receiver at between about 700-900 inch pounds. So,as the closure structure 1018 and the rod 1021 press the insert 1014downwardly toward the base of the receiver 1010, the insert surfaces1175′ are forced into the receiver at the edges 1097, thus forcing andfixing the insert 1014 into frictional interference engagement with thereceiver surfaces 1071.

With reference to FIG. 99, at this time, the closure top 1018 may beloosened or removed and/or the rod 1021 may be adjusted and/or removedand the frictional engagement between the insert 1014′ and the receiver1010 at the insert surfaces 1175′ will remain locked in place,advantageously maintaining a locked angular position of the shank 1004with respect to the receiver 1010.

With further reference to FIGS. 99 and 100, at this time, another rod,such as the deformable rod 1221 and cooperating alternative closure top1218 may be loaded onto the already locked-up assembly to result in analternative assembly 1201′. As mentioned above, the closure drive 1286may advantageously be made smaller than the drive of the closure 1018,such that the deformable rod 1221 is not unduly pressed or deformedduring assembly since the polyaxial mechanism is already locked.

With reference to FIGS. 101-103, a two-piece tool 1600 is illustratedfor releasing the insert 1014′ from the receiver 1010. The tool 1600includes an inner flexible tube-like structure with opposed inwardlyfacing prongs 1612 located on either side of a through-channel 1616. Thechannel 1616 may terminate at a location spaced from the prongs 1612 ormay extend further upwardly through the tool, resulting in a two-piecetool 1610. The tool 1600 includes an outer, more rigid tubular member1620 having a smaller through channel 1622. The member 1620 slidinglyfits over the tube 1610 after the flexible member 1610 prongs 1612 areflexed outwardly and then fitted over the receiver 1010 and then withinthrough bores of the opposed apertures 1074 of the receiver 1010 andaligned opposed bores 1166′ located on arms of the insert 1014′. In FIG.101, the tool 1600 is shown during the process of unlocking the insert1014′ from the receiver 1010 with the outer member 6120 surrounding theinner member 1610 and holding the prongs 1612 within the receiver 1010and insert 1014′ apertures while the tool 1600 is pulled upwardly awayfrom the shank 1004. It is foreseen that the tool 1600 may furtherinclude structure for pressing down upon the receiver 1010 while theprongs and tubular member are pulled upwardly, such structure may belocated within the tool 1600 and press down upon the top surfaces 1073of the receiver arms, for example.

Alternatively, another manipulation tool (not shown) may be used that isinserted into the receiver at the opening 1066 and into the insertchannel formed by the saddle 1153′, with prongs or extensions thereofextending outwardly into the insert through bores 1166′; a piston-likeportion of the tool thereafter pushing directly on the shank upperportion 1008, thereby pulling the insert 1014′ away from the receiversurface 1090 and thus releasing the polyaxial mechanism. At such time,the shank 1004 may be articulated with respect to the receiver 1010, andthe desired friction fit returns between the retainer 1012 and the shanksurface 1034, so that an adjustable, but non-floppy relationship stillexists between the shank 1004 and the receiver 1010. If furtherdisassembly if the assembly is desired, such is accomplished in reverseorder to the procedure described previously herein for the assembly1001.

With reference to FIGS. 104-106, another manipulation tool, generally1700 is illustrated for independently locking the insert 1014′ to thereceiver 1010. The tool 1700 includes a pair of opposed arms 1712, eachhaving an engagement extension 1716 positioned at an oblique angle withrespect to the respective arm 1712 such that when the tool is moveddownwardly toward the receiver, one or more inner surfaces 1718 of theengagement extension 1716 slide along the surfaces 1077 of the receiverand 1167′ of the insert 1014′ to engage the insert 1014′, with a surface1720 pressing downwardly on the insert surfaces 1168′, pushing theplanar surfaces 1175′ into an interference locking fit within thereceiver edge 1097 and surfaces 1072. As shown in FIG. 106, when theinsert 1014′ is locked against the receiver 1010, the tool bottomsurfaces 1720 do not bottom out on the receiver surfaces 1075′, butremain spaced therefrom. In the illustrated embodiment, the surface 1718is slightly rounded and each arm extension 1716 further includes aplanar lower surface 1722 that creates an edge with the bottom surface1720 for insertion and gripping of the insert 1014′ at the juncture ofthe surface 1167′ and the surface 1168′. The tool 1700 may include avariety of holding and pushing/pulling mechanisms, such as a pistol griptool, that may include a ratchet feature, a hinged tool, or, a rotatablythreaded device, for example.

It is to be understood that while certain forms of the present inventionhave been illustrated and described herein, it is not to be limited tothe specific forms or arrangement of parts described and shown.

What is claimed is:
 1. A pivotal bone anchor assembly configured forarrangement with tooling prior to securement of an elongate rod to abone of a patient via a closure top, the pivotal bone anchor assemblycomprising: a receiver comprising a base defining a central boreextending along a longitudinal axis and in communication with a bottomof the receiver through a lower opening, and an upper portion extendingupwardly from the base to define an open channel configured to receivethe elongate rod, the central bore extending upward through the openchannel to a top of the receiver and including at least one interiorinterference structure protruding inwardly into the central bore andhaving a discontinuous annular upper surface; and a shank comprising ahead configured for positioning within the central bore and an anchorportion opposite the head configured for fixation to the bone; an insertconfigured for positioning into an initial position in the central boreseparate from the head of the shank, the insert in the initial positionconfigured to be constrained from vertical movement along thelongitudinal axis of the receiver in at least one direction byengagement between outer curvate side surfaces of the insert and thediscontinuous annular upper surface of the at least one interiorinterference structure; wherein after the head of the shank ispositioned within the central bore and prior to the elongate rod beingsecured within the open channel via the closure top, the insert isconfigured for forced downward displacement within the central bore bythe tooling from the initial position to a lower position in which theouter curvate side surfaces of the insert are wedged against the atleast one interior interference structure with an interferenceengagement so as to inhibit the insert from moving back up within thecentral bore of the receiver.
 2. The pivotal bone anchor assembly ofclaim 1, wherein the discontinuous annular upper surface of the at leastone interior interference structure further comprises a planar surfacesubstantially perpendicular to the longitudinal axis of the receiver. 3.The pivotal bone anchor assembly of claim 1, wherein the at least oneinterior interference structure includes a partially discontinuouscylindrical surface.
 4. The pivotal bone anchor assembly of claim 1,wherein the insert further comprises an upper saddle surface configuredto engage the elongate rod.
 5. The pivotal bone anchor assembly of claim1, wherein the insert is configured to be top-loaded into the receiver.6. The pivotal bone anchor assembly of claim 1, wherein the insert isconfigured to be positioned within the central bore of the receiverprior to the head of the shank.
 7. The pivotal bone anchor assembly ofclaim 1, wherein the insert includes a central through-bore sized andshaped to receive tooling configured to engage a drive structure formedinto the head of the shank.
 8. The pivotal bone anchor assembly of claim1, further comprising a retainer configured to be positioned within thecentral bore of the receiver so as to capture and hold the head of theshank therein.
 9. The pivotal bone anchor assembly of claim 8, whereinthe retainer is configured to be positioned within the central bore ofthe receiver prior to the head of the shank.
 10. The pivotal bone anchorassembly of claim 8, wherein the retainer is configured to benon-pivoting with respect to the receiver.
 11. The pivotal bone anchorassembly of claim 8, wherein the retainer includes at least one of aslit or slot extending through a thickness thereof and configured toallow for an expansion of the retainer around the head of the shank uponan uploading of the head into the central bore of the receiver throughthe lower opening.
 12. The pivotal bone anchor assembly of claim 11,wherein the retainer is configured to be held in an expansion region ofthe central bore prior to capturing the head of the shank.
 13. Thepivotal bone anchor assembly of claim 1, further comprising the closuretop, wherein the closure top is configured to engage the elongate rodwithout contacting the insert when the elongate rod is secured withinthe open channel.
 14. The pivotal bone anchor assembly of claim 1,further comprising the closure top, wherein the closure top isconfigured to be rotated into engagement with the upper portion of thereceiver to secure the elongate rod within the open channel.
 15. Apivotal bone anchor assembly configured for arrangement with adisplacement tool prior to securement of an elongate rod to a bone of apatient via a closure top, the pivotal bone anchor assembly comprising:a receiver comprising a base defining a central bore centered about alongitudinal axis and in communication with a bottom of the receiverthrough a lower opening, and a pair of upright arms extending upwardlyfrom the base to define an open channel configured to receive theelongate rod, the central bore extending upward through the open channelto a top of the receiver and including at least one inwardly-protrudinginterference structure defining an upward-facing discontinuous annularsurface in the interior of the upright arms; a shank comprising a headconfigured for positioning within the central bore and an anchor portionopposite the head configured for fixation to the bone; an insertconfigured for positioning into an initial position in the central boreseparate from the head of the shank, the insert in the initial positionconfigured to be constrained from vertical movement along thelongitudinal axis of the receiver in at least one direction byengagement between outer curvate side surfaces of the insert and thediscontinuous annular surface, wherein after the head of the shank isreceived within the central bore and prior to the elongate rod beingsecured within the open channel via the closure, the insert isconfigured for forced downward displacement within the central bore fromthe initial position to a deployed position by direct engagement withthe displacement tool, the insert in the deployed position having aninterference fit engagement between the outer curvate side surfaces ofthe insert and the at least one inwardly-protruding interferencestructure so as to inhibit the insert from moving back up within thecentral bore of the receiver.
 16. The pivotal bone anchor assembly ofclaim 15, wherein the at least one inwardly-protruding interferencestructure includes a partially discontinuous cylindrical surface. 17.The pivotal bone anchor assembly of claim 15, wherein the insert furthercomprises an upper saddle surface configured to engage the elongate rod.18. The pivotal bone anchor assembly of claim 15, wherein the insert isconfigured to be top-loaded into the receiver.
 19. The pivotal boneanchor assembly of claim 15, wherein the insert is configured to bepositioned within the central bore of the receiver prior to the head ofthe shank.
 20. The pivotal bone anchor assembly of claim 15, wherein theinsert includes a central through-bore sized and shaped to receive adrive tool configured to engage a drive structure formed into the headof the shank.
 21. The pivotal bone anchor assembly of claim 15, furthercomprising a retainer configured to be positioned within the centralbore of the receiver so as to capture and hold the head of the shanktherein.
 22. The pivotal bone anchor assembly of claim 21, wherein theretainer is configured to be positioned within the central bore of thereceiver prior to the head of the shank.
 23. The pivotal bone anchorassembly of claim 22, wherein the retainer is configured to benon-pivoting with respect to the receiver.
 24. The pivotal bone anchorassembly of claim 22, wherein the retainer includes at least one of aslit or slot extending through a thickness thereof and configured toallow for an expansion of the retainer around the head of the shank uponan uploading of the head into the central bore of the receiver throughthe lower opening.
 25. The pivotal bone anchor assembly of claim 24,wherein the retainer is configured to be held in an expansion region ofthe central bore prior to capturing the head of the shank.
 26. Thepivotal bone anchor assembly of claim 15, further comprising the closuretop, wherein the closure top is configured to engage the elongate rodwithout contacting the insert when the elongate rod is secured withinthe open channel.
 27. The pivotal bone anchor assembly of claim 15,further comprising the closure top, wherein the closure top isconfigured to be rotated into engagement with the upper portion of thereceiver to secure the elongate rod within the open channel.